Introduction to the World of Physics: teaching manual 9786010410916

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AL-FARABI KAZAKH NATIONAL UNIVERSITY

L. E. Strautman Sh. B. Gumarova N. K. Sabyrbaeva

INTRODUCTION TO THE WORLD OF PHYSICS Teaching manual

Almaty «Qazaq university» 2015

UDC 530.1 (075.8) LBC 22.3 я 73 S 81 Recommended by the Scientific Council of the Faculty of Philology, Literary Studies and World Languages

Reviewed by: doctor of Pedagogical sciences I.F. Smailova candidate of Pedagogical sciences S.G. Tazhbaeva

S 81

Strautman L.E. Introduction to the World of Physics: teaching manual / L.E. Strautman, Sh.B. Gumarova, N.K. Sabyrbaeva. – Almaty: Qazaq university, 2015. – 164 p. ISBN 978-601-04-1091-6 The teaching manual is intended for classroom activities for 1-2-year students of the Faculty of Physics and Technology, specialties «physics», «technical physics», «nuclear physics», and it can also be used as supplementary material for self-study assignments.

UDC 530.1 (075.8) LBC 22.3 я 73

ISBN 978-601-04-1091-6

© Strautman L.E., Gumarova Sh.B., Sabyrbaeva N.K., 2015 © Al-Farabi KazNU, 2015

LESSON 1 Active vocabulary Measurement 1) из­ме­ре­ние; за­мер 2) раз­ме­ры Measure 1) ме­ра; еди­ни­ца из­ме­ре­ния The measure is given in centimeters. – Еди­ни­цей из­ме­ре­ния яв­ляет­ся сан­ти­метр. dry measures – ме­ры сы­пу­чих тел liquid measures – ме­ры жид­кос­тей square measures – ме­ры пло­ща­ди – linear measures 2) мер­ка, раз­мер, ме­ра, эта­лон, ос­но­ва­ние (для че­го-л.) Wealth is not a measure of happiness. – Бо­га­тс­тво не мо­жет слу­жить ме­ри­ лом счас­тья. 3) а) необ­хо­ди­мое ко­ли­че­ст­во, ме­ра б) ме­ра, уме­рен­ность, сдер­жан­нос­ть в) грань, гра­ни­ца, сте­пень, пре­дел 1) ме­ра; еди­ни­ца из­ме­ре­ния The measure is given in centimeters. – Еди­ни­цей из­ме­ре­ния яв­ляет­ся сан­ти­метр. dry measures – ме­ ры сы­пу­чих тел liquid measures – ме­ры жид­кос­тей square measures – ме­ры пло­ща­ди – linear measures 2) а) мер­ка, раз­мер He liked suits made to measure. – Он лю­бил кос­тю­мы, сши­тые на за­каз. б) ме­ра, эта­лон, ос­но­ва­ние (для че­го-л.) Wealth is not a measure of happiness. – Бо­га­тс­тво не мо­жет слу­жить ме­ри­лом счас­тья. 3) а) необ­хо­ди­мое ко­ли­че­ст­во, ме­ра б) ме­ра, уме­рен­ность, сдер­ жан­нос­ть в) грань, гра­ни­ца, сте­пень, пре­дел Rod стер­жень, брус, рей­ка, тя­га, шток, ры­чаг connecting rod – соеди­ни­тель­ная тя­га, ша­тун divining rod – вол­шеб­ный (иво­вый) прут для отыс­ка­ния под­поч­вен­ных вод или ме­тал­лов lightning rod – стерж­не­вой мол­ниеот­вод piston rod – шток порш­ня fuel rod – ура­но­вый стер­жень (в ядер­ном реак­то­ре) Comparison со­пос­тав­ле­ние, срав­не­ние, there is no comparison between them – не­воз­мож­но их срав­ни­вать To define 1) (define as) оп­ре­де­лять (зна­че­ние сло­ва), да­вать оп­ ре­де­ле­ние (ка­ко­му-л. по­ня­тию) 2) за­дать (про­це­ду­ру); оп­ре­де­лить, опи­сать (пе­ре­мен­ную) 3) очер­чи­вать, ог­ра­ни­чи­вать, устанав­ли­вать гра­ни­цы rigidly defined property lines – ст­ро­го оп­ре­делённые гра­ни­цы собст­вен­нос­ти Syn: demarcate 4) ха­рак­те­ри­зо­вать; оп­ре­де­лять, устанав­ли­вать to define smb.’s powers – оп­ре­де­лить чьи-л. Пол­но­мо­чия To determine 1) оп­ре­де­лять, устанав­ли­вать2) ре­шать, раз­ре­ шать to determine a dispute – ре­шить спор Syn: decide, resolve, 3) оп­ре­де­лять, ре­шать, вы­но­сить ре­ше­ние Syn: resolve 4) (deter-

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Introduction to the World of Physics

mine to do smth. / (up)on doing smth.) ре­шать, при­ни­мать ре­ше­ние (сде­лать что-л.) error bound гра­ни­ца (пре­дел) пог­реш­нос­ти error margin до­пус­ти­мая пог­реш­нос­ть; до­пус­ти­мый пре­дел estimate 1) оцен­ка by smb.’s estimate – по чьей-л. оцен­ке to give / make estimate – оце­ни­вать an approximate, rough estimate – гру­ бая оцен­ка conservative estimate – кон­сер­ва­тив­ная точ­ка зре­ния preliminary estimate – пред­ва­ри­тель­ная оцен­ка written estimate – пись­менная оцен­ка meter scale шка­ла из­ме­ри­тель­но­го при­бо­ра confidence level 1) до­ве­ри­тель­ный уро­вень; уро­вень до­ве­ри­ тель­ной ве­роят­нос­ти 2) уро­вень дос­то­вер­нос­ти; сте­пень уве­рен­нос­ти quantity 1) ко­ли­че­ст­во; чис­лен­нос­ть, чис­ло in (large) quantities – в (боль­шом) ко­ли­че­ст­ве considerable quantity – зна­чи­тель­ное ко­ли­че­ст­во large quantity – боль­шое ко­ли­че­ст­во small quantity – нез­на­чи­тель­ное ко­ли­че­ст­во sufficient quantity – дос­та­точ­ное ко­ли­ че­ст­во 4) ве­ли­чи­на derived quantity – произ­вод­ная ве­ли­чи­на incommensurable quantities – не­со­из­ме­ри­мые ве­ли­чи­ны negligible quantity – пре­неб­ре­жи­мо ма­лая ве­ли­чи­на unknown quantity – неиз­ ве­ст­ная ве­ли­чи­на British Imperial system бри­та­нс­кая, анг­лий­ская или им­пе­рс­ кая сис­те­ма еди­ниц из­ме­ре­ния (в от­ли­чие от мет­ри­чес­кой) Text 1

Units of measurement

Measurement is a process that uses numbers to describe things based on what we can observe about them. This is done to be able to compare them to each other. We can measure how big things are, how warm they are, how heavy they are, and lots of other features as well. Units of Measurement provide standards for our comparisons, so that the numbers from our measurements refer to the same thing. For example, the meter is a standard unit used to measure length. Before 1982, it was defined as the distance between two markers on a special rod. Now scientists define the meter as a fraction of the speed of light. Saying something has a length of 2 meters means that it is exactly twice as long as that rod used to define the meter, or that light takes twice the time defined for a meter to travel that distance.

Lesson 1

The act of measuring often requires an instrument designed and calibrated for that purpose, such as a thermometer, speedometer, weighing scale, or voltmeter. The property of the thing being measured is given as a number of units of measurement. The number only has sense when the unit of measurement is also given. For example, the Eiffel Tower in Paris, France is 300 meters tall. That is, the distance from the top to the bottom of the Eiffel Tower is 300 meters. The property of the Eiffel Tower being measured is a distance. The number measured is 300. This number does not make sense without the unit of measurement. The unit of measurement is the meter. Standards are special objects that are used to make measurements in terms of fixed units of measurement. A meter stick is an example of a standard. When you measure something with a meter stick, you can compare that measurement to anything else that is also measured with a meter stick. This makes measurement easier and comparisons between measurements easier. There are units of measurement of different sizes. There are small units of measurement to measure small things. There are big units of measurement to measure big things. Science, medicine and engineering use smaller units of measurement to measure small things with less error. It is easier to measure large things using larger units of measurement. Large measurements like the width of a galaxy and small measurements like the mass of an atom use special units of measurement. Measurement is fundamental in science; it is one of the things that distinguish science from pseudoscience. Measurement is also essential in industry, commerce, engineering, construction, manufacturing, pharmaceutical production, and electronics. The word measurement comes from the Greek «metron,» meaning limited proportion. This also has a common root with the word «moon» and «month» possibly since the moon and other astronomical objects were among the first measurement methods of time. The history of measurements is a topic within the history of science and technology. The meter (or metre) was standardized as the unit for length after the French revolution, and has since been adopted throughout most of the world.

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– «When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of science». – Lord Kelvin Measurements always have errors and therefore uncertainties. In fact, the reduction – not necessarily the elimination – of uncertainty is central to the concept of measurement. Measurement errors are often assumed to be normally distributed about the true value of the measured quantity. Under this assumption, every measurement has three components: the estimate, the error bound, and the probability that the actual magnitude lies within the error bound of the estimate. For example, a measurement of the length of a plank might result in a measurement of 2.53 meters plus or minus 0.01 meter, with a probability of 99 percent. In science, where accurate measurement is crucial, a measurement is understood to have three parts: first, the measurement itself, second, the margin of error, and third, the confidence level – that is, the probability that the actual property of the physical object is within the margin of error. For example, we might measure the length of an object as 2.34 meters plus or minus 0.01 meter, with a 95 percent level of confidence. Task №1 Answer the questions. 1. Where does the word measure come from? 2. What can we measure? 3. Who define the meter as a fraction of the speed of light? 4. Are there units of measurement of different sizes? 5. Where is measurement also essential? Task №2 Make questions to the underlined words Measurement is a process that uses numbers to describe things based on what we can observe about them.

Lesson 1 The act of measuring often requires an instrument designed and calibrated for that purpose, such as a thermometer, speedometer, weighing scale, or voltmeter. Standards are special objects that are used to make measurements in terms of fixed units of measurement. Measurement errors are often assumed to be normally distributed about the true value of the measured quantity. Every measurement has three components: the estimate, the error bound, and the probability that the actual magnitude lies within the error bound of the estimate. Task №3 Put the verb into the correct form. 1.The word measurement ___from the Greek «metron», meaning limited proportion. (come) 2. The act of measuring often_____ an instrument designed and calibrated for that purpose, such as a thermometer, speedometer, weighing scale, or voltmeter.( requires) 3. The distance from the top to the bottom of the Eiffel Tower is 300 meters. The number ____ is 300. (measured) 4. Science, medicine and engineering ____smaller units of measurement to measure small things with less error. (use) 5. The unit of measurement __ the meter. (to be) Task №4 Put the verb into active or passive form. 1.This _____ to be able to compare them to each other. (do) 2. Before 1982, it _______ as the distance between two markers on a special rod. (define) 3. Standards are special objects that _____ to make measurements in terms of fixed units of measurement.(use) 4. The meter (or metre)_____ (standardize) as the unit for length after the French revolution, and __since ___(adopt) throughout most of the world. 5. Measurement errors ___often ___(assum) to be normally distributed about the true value of the measured quantity. Task №5 Complete the sentences using one of these verbs. come provide make require define 1. Units of Measurement _____standards for our comparisons, so that the numbers from our measurements refer to the same thing. 2. Now scientists _____the meter as a fraction of the speed of light. 3. The act of measuring often _____an instrument designed and calibrated for that purpose, such as a thermometer, speedometer, weighing scale, or voltmeter. 4. Standards are special objects that are used to ______measurements in terms of fixed units of measurement. 5. The word measurement _____from the Greek «metron,» meaning limited proportion.

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Introduction to the World of Physics Task №6 Put in a/an or the where necessary. ____ Eiffel Tower in Paris, France is 300 meters tall. That is, ____ distance from ____top to ____ bottom of ____ Eiffel Tower is 300 meters. ____ property of ____ Eiffel Tower being measured is ___distance. ____number measured is 300. This number does not make sense without ____unit of measurement. ___ meter stick is ___example of a standard. Large measurements like ___ width of a galaxy and small measurements like ___mass of ___ atom use special units of measurement. ___measurement of ___length of ___ plank might result in ___measurement of 2.53 meters plus or minus 0.01 meter, with __ probability of 99 percent.

LESSON 2 Active vocabulary Imperial units – Им­пе­рс­кие еди­ни­цы Emergence – появ­ле­ние customary units – обыч­ные еди­ни­цы to adopt – при­нять remain – ос­тать­ся

gallon – гал­лон despite – нес­мот­ря на imperial fluid ounce – им­пе­рс­кая жид­кая ун­ция inch – дюйм, дюй­мо­вый, мед­лен­ но дви­гать­ся

Text 2 Systems of measurement Before SI units were widely adopted around the world, the British systems of English units and later Imperial units were used in Britain, the Commonwealth and the United States. The system came to be known as U.S. customary units in the United States and is still in use there and in a few Caribbean countries. These various systems of measurement have at times been called foot-pound-second systems after the Imperial units for distance, weight and time. Many Imperial units remain in use in Britain despite the fact that it has officially switched to the SI system. Road signs are still in miles, yards, miles per hour, and so on, people tend to measure their own height in feet

Lesson 2

and inches and milk is sold in pints, to give just a few examples. Imperial units are used in many other places, for example, in many Commonwealth countries that are considered metricated, land area is measured in acres and floor space in square feet, particularly for commercial transactions (rather than government statistics). Similarly, the imperial gallon is used in many countries that are considered metricated at gas/petrol stations, an example being the United Arab Emirates. The metric system is a system of measurement used in most of the world. It is also called the International System of Units, or SI. British imperial Units Imperial units were defined in the United Kingdom in 1825. Imperial units were used in countries that were part of the British Empire. While many of these countries, including the United Kingdom, have officially adopted SI, the older system of units is still used US customary units are the official units used in the US. These are similar to the British imperial units and are also based on the units used in the United Kingdom from before American Independence. But some of the units are different to the British ones. For example, there are 20 imperial fluid ounces in an imperial pint, but 16 US fluid ounces in a US pint. Additionally, the US fluid ounce is slightly bigger than the imperial fluid ounce. The result is that US pints and gallons are smaller than imperial pints and gallons. In the United States, the metric system has been legal for trade since 1866 but other measurements such as the gallon, inch, and the pound are still widely used. SI Units are the most widely used system of units. They are the most common system for everyday commerce in the world, and are almost universally used in the realm of science. The name derives from the French phrase, Système International d’Unités, or in English International System of Units. The system consists of a set of seven base units together with a set of prefixes from which all other units are derived. The emergence of an internationally recognized system of units at a time of increasing international cooperation and trade is highly significant. It has provided a necessary common base for the scientific, technical, and industrial exchange that has fostered a growing consciousness of the need to approach issues from a global perspective. The metric system was officially adopted in France after the French Revolution. During the history of the metric system, a number

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of variations have evolved and their use spread around the world replacing many traditional measurement systems. By the end of World War II a number of different systems of measurement were still in use throughout the world. Some of these systems were metric system variations while others were based on the Imperial and American systems. It was recognized that additional steps were needed to promote a worldwide measurement system. As a result, the 9th General Conference on Weights and Measures (CGPM) in 1948, asked the International Committee for Weights and Measures (CIPM) to conduct an international study of the measurement needs of the scientific, technical, and educational communities. Based on the findings of this study, the 10th CGPM in 1954 decided that an international system should be derived from six base units to provide for the measurement of temperature and optical radiation in addition to mechanical and electromagnetic quantities. The six base units recommended were the meter, kilogram, second, ampere, Kelvin (later renamed kelvin), and the candela. In 1960, the 11th CGPM named the system the International System of Units. The seventh base unit, the mole, was added in 1970 by the 14th CGPM. SI units are still sometimes referred to as the metric system, especially in the United States, whose population has not widely adopted it, and in the United Kingdom, where conversion is only partial. SI units are a specific canon of measurements derived and extended from the Metric system; however, not all metric units of measurement are accepted as SI units. This international system of units is now either obligatory or permissible throughout the world. It is administered by the standards organization: the Bureau International des Poids et Mesures (International Bureau of Weights and Measures, BIPM). Length The most important unit is length: one meter was originally defined to be equal to 1/10,000,000th of the distance from the pole to the equator along the meridian through Paris. (Prior discussions had often suggested the length of a seconds pendulum in some standard gravity, which would have been only slightly shorter, and perhaps easier to determine.) This is approximately 10 percent longer than one yard. Later on, a platinum rod with a rigid, X-shaped cross section was produced to serve as the easy-to-check standard for one meter’s length. Due to the difficulty of actually measuring the length of a meridian

Lesson 2

quadrant in the eighteenth century, the first platinum prototype was short by 0.2 millimeters. More recently, the meter was redefined as a certain multiple of a specific radiation wavelength, and currently it is defined as the distance traveled by light in a vacuum in a specific period of time. Attempts to relate an integer multiple of the meter to any meridian have been abandoned. Mass The original base unit of mass in the metric system was the gram, chosen to match the mass of one cubic centimeter of water. For practical reasons, the reference standard that was deposited at the Archives de la république on June 22, 1799, was a kilogram (a cylinder of platinum). One kilogram is about 2.2 pounds. In 1889, the first General Conference on Weights and Measures (CGPM) sanctioned a replacement prototype, a cylinder of a 90 percent platinum, 10 percent iridium alloy; this has served as the standard ever since and is stored in a Paris vault. The kilogram became the base unit in 1901. Also in 1901, a kilogram of distilled pure water at its densest (+3.98° C) under a standard atmosphere of pressure was used to define the liter, a more convenient unit than the very large cubic meter. Because this liter turned out to be different from the cubic decimeter by about 28 millionths, this definition was abandoned in 1964 in favor of the cubic decimeter. The kilogram is the only base unit not to have been redefined in terms of an unchanging natural phenomenon. Such a definition, said to be in terms of an artefact (the cylinder in Paris), is particularly inconvenient, because, in principle, it can be used only by traveling to Paris and, with permission, comparing one’s own candidate standard to the reference one. For this reason, as well as the effort required to protect the standard from absorption or dispersion of gases and vapors, at a meeting of the Royal Society in London on February 15, 2005, scientists called for the mass of the standard kilogramme in Paris to be replaced by a standard based on «an invariable property of nature»; but no decision on redefinition can be taken before 2007. Temperature The metric unit of temperature originally was the centigrade or Celsius scale. This was determined by divided into 100 equal-length parts the difference between a water-ice mixture at 0° C and the boiling

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point of pure distilled water at 100° C (under a standard atmosphere). This is still the metric unit of temperature in everyday use. With the discovery of absolute zero, a new temperature scale, the Kelvin Scale was developed, which relocates the zero point to absolute zero. The freezing point of water, 0° C, becomes 273.15 K. It is the Kelvin scale that is used as the base SI unit. Time The metric unit of time is the second. It was originally defined as 1/86,400th of a mean solar day. The formal definition of the second has been changed several times as more accurate definitions became possible, based first on astronomic observations, then the tuning fork clock, quartz clock, and today the cesium atomic clock SI prefixes The SI system of units is a metric system. That is, the units are expressed in powers of 10 (i.e. 1×10 3 ). In order to simplify writing the powers of ten, they are expressed as prefixes and the symbol for the prefix put before the unit. Thus, 7.4×10 3 m is written as 7.4 km. The following SI prefixes can be used to prefix any of the units to produce a multiple or submultiple of the original unit. This includes the degree Celsius (e.g. «1.2 m°C»); however, to avoid confusion, prefixes are not used with the time-related unit symbols min (minute), h (hour), d (day). They are not recommended for use with the anglerelated symbols ° (degree), ‘ (minute of arc), and «(second of arc), but for astronomical usage, they are sometimes used with seconds of arc. Task №1 Answer the questions. 1. What units were used in Britain? What is a system of measurement used in most of the world? When were Imperial units defined in the United Kingdom? Is the most important unit length or mass? The metric unit of time is the first, isn’t it? Task №2 Put the verb into active or passive form. 1.Before SI units _____widely around the world, the British systems of English units and later Imperial units were used in Britain, the Commonwealth

Lesson 2 and the United States. (adopt) 2. These various systems of measurement ___at times ____ foot-pound-second systems after the Imperial units for distance, weight and time. (call) 3. Imperial units ___in many other places, for example, in many Commonwealth countries that ____ metricated, land area is measured in acres and floor space in square feet. (use)/ (consider) 4. Imperial units ____ in countries that were part of the British Empire (use).5. The metric system ___ officially in France after the French Revolution. (adopt) Task №3 Put in a/an or the where necessary. 1. There are 20 imperial fluid ounces in ___imperial pint, but 16 US fluid ounces in ___US pint. 2. Additionally, ___US fluid ounce is slightly bigger than ___ imperial fluid ounce. 3. ___emergence of __internationally recognized system of units at __ time of increasing international cooperation and trade is highly significant. 4. During __history of __metric system, __number of variations have evolved and their use spread around __ world replacing many traditional measurement systems.5. ___International Committee for Weights and Measures (CIPM) to conduct ___international study of the measurement needs of ___ scientific, technical, and educational communities. Task №4 Put in the missing preposition. 1.The metric system is a system ___ measurement used in most ____ the world. 2. These are similar ___the British imperial units and are also based ___ the units used ___ the United Kingdom __before American Independence. But some ___ the units are different___the British ones. 3. The most important unit is that___ length: one meter was originally defined to be equal ___1/10,000,000th ___ the distance ___the pole ___ the equator ___ the meridian ___ Paris.4. The name derives __ the French phrase, Système International d’Unités, or __ English International System __ Units. 5. The system consists of a set __seven base units together ___ a set ___ prefixes ___ which all other units are derived. Task №5 Put the verb into the correct form. 1.The original base unit of mass in the metric system ___ the gram. (to be) 2. In 1889, the first General Conference on Weights and Measures (CGPM) ____a replacement prototype, a cylinder of a 90 percent platinum, 10 percent iridium alloy. (sanction)3. This ___as the standard ever since and is stored in a Paris vault. (serve) 4. The kilogram ____the base unit in 1901.( become) 5. The formal definition of the second ____several times as more accurate definitions ___possible, based first on astronomic observations, then the tuning fork clock, quartz clock, and today the cesium atomic clock. (change/ become)

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Introduction to the World of Physics Task №6 Complete the sentence. Use the comparative or superlative form. 1. The result is that US pints and gallons are (small) imperial pints and gallons. 2. They are (common) system for everyday commerce in the world.3. The US fluid ounce is slightly (big) the imperial fluid ounce. 4. The result is that US pints and gallons are (small) imperial pints and gallons. 5. Prior discussions had often suggested the length of a seconds pendulum in some standard gravity, which would have been only slightly (short), and perhaps (easy) to determine.) This is approximately 10 percent (long) one yard. Task №7 Make questions to the underlined words Imperial units were used in countries that were part of the British Empire. 1. In the United States, the metric system has been legal for trade since 1866 but other measurements such as the gallon, inch, and the pound are still widely used. 2. The original base unit of mass in the metric system was the gram, chosen to match the mass of one cubic centimeter of water. 3. The kilogram is the only base unit not to have been redefined in terms of an unchanging natural phenomenon. 4. The metric unit of time is the second. It was originally defined as 1/86,400th of a mean solar day.

LESSON 3 Active vocabulary Superconductivity – Сверх­про­во­ ди­мос­ть discover – об­на­ру­жить phenomenon – яв­ле­ние occur – прои­зойти electrical resistance – элект­ри­чес­ кое соп­ро­тив­ле­ние exclusion – иск­лю­че­ние interior – ин­терь­ер property – собст­вен­ность

digital circuits – циф­ро­вые схе­мы microwave filter – мик­ро­вол­но­вый филь­тр storage devices – уст­рой­ст­ва хра­ не­ния дан­ных abruptly – рез­ко impose – на­ло­жить electrical current – элект­ри­чес­кий ток cryogenic temperatures – крио­ген­ ные тем­пе­ра­ту­ры refrigerant – хла­да­гент

Lesson 3

Text 3 Superconductivity Superconductivity, discovered in 1911 by Heike Kamerlingh Onnes, is a phenomenon occurring in certain materials at extremely low temperatures (on the order of − 200 degrees Celsius), characterized by exactly zero electrical resistance and exclusion of the interior magnetic field (the Meissner effect). Materials with such properties are called superconductors. Superconductors are used to make some of the most powerful electromagnets known to man, including those used in MRI machines. They have also been used to make digital circuits, highly sensitive magnetometers, and microwave filters for mobile phone base stations. They can also be used for the separation of weakly magnetic particles from less magnetic or nonmagnetic particles, as in the pigment industries. Promising future applications include high-performance transformers, power storage devices, electric power transmission, electric motors (such as for maglev trains), and magnetic levitation devices. The electrical resistivity (the measure of how much a material resists an electric current) of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, impurities and other defects impose a lower limit. Even near absolute zero, a sample of copper shows non-zero resistance. The resistance of a superconductor, on the other hand, drops abruptly to zero when the material is cooled below a temperature called its «critical temperature» – typically 20 Kelvin (K) or less. An electrical current flowing in a loop of superconducting wire will persist indefinitely with no power source (provided that no energy is drawn from it). Superconductivity occurs in a wide variety of materials, including simple elements like tin and aluminum, various metallic alloys, and certain kinds of ceramic materials known as high-temperature superconductors (HTS). Superconductivity does not occur in noble metals like gold and silver, nor in most metals that can be spontaneously magnetized. In 1986, the discovery of HTS, with critical temperatures in excess of 90 K, spurred renewed interest and research in superconductivity for several reasons. As a topic of pure research, these materials represented

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a new phenomenon not explained by the current theory. Also, because the superconducting state persists up to more manageable temperatures, more commercial applications become feasible, especially if materials with even higher critical temperatures could be discovered. History of superconductivity Superconductivity was discovered in 1911 by Heike Kamerlingh Onnes, who was studying the resistance of solid mercury at cryogenic temperatures using the recently discovered liquid helium as a refrigerant. At the temperature of 4.2 K, he observed that the resistance abruptly disappeared. For this discovery, he was awarded the Nobel Prize in Physics in 1913. In subsequent decades, superconductivity was found in several other materials. In 1913, lead was found to be superconductive at 7 K, and in 1941 niobium nitride was found to be superconductive at 16 K. The next important step in understanding superconductivity occurred in 1933, when Walter Meissner and Robert Ochsenfeld discovered that superconductors expelled applied magnetic fields, a phenomenon that has come to be known as the «Meissner effect.» In 1935 F. and H. London showed that the Meissner effect was a consequence of the minimization of the electromagnetic free energy carried by superconducting current. In 1950 Lev Landau and Vitaly Ginzburg formulated what came to be called the phenomenological Ginzburg-Landau theory of superconductivity. This theory had great success in explaining the macroscopic properties of superconductors. In particular, Alexei Abrikosov showed that the theory predicts the division of superconductors into the two categories, now referred to as Type I and Type II. Abrikosov and Ginzburg were awarded the 2003 Nobel Prize for their work (Landau died in 1968). Also in 1950, James Maxwell and Reynolds et al. found that the critical temperature of a superconductor depends on the isotopic mass of the constituent element. This discovery revealed that the internal mechanism responsible for superconductivity was related to the attractive force between electrons and the ion lattice beneath – known as electron-phonon interactions. The complete, microscopic theory of superconductivity was finally proposed in 1957 by John Bardeen (1908-1991), Leon Cooper, and John Schrieffer. It came to be known as the BCS theory. Superconductivity

Lesson 3

was independently explained by Nikolay Bogolyubov (1909-1992). The BCS theory explained the superconducting current as a superfluid of «Cooper pairs» – pairs of electrons interacting through the exchange of phonons. For this work, the authors were awarded the Nobel Prize in 1972. In 1959 Lev Gor’kov showed that the BCS theory becomes equivalent to the Ginzburg-Landau theory close to the critical temperature. Generalizations of these theories form the basis for understanding the closely related phenomenon of superfluidity (because they fall into the Lambda transition universality class), but the extent to which similar generalizations can be applied to unconventional superconductors is still controversial. In 1962 the first commercial superconducting wire, a niobiumtitanium alloy, was developed by researchers at Westinghouse Electric Corporation. In the same year, Brian Josephson made the important theoretical prediction that a supercurrent can flow between two pieces of superconductor separated by a thin layer of insulator. This phenomenon, now called the «Josephson effect» is exploited by superconducting devices such as SQUIDs (superconducting quantum interference devices). Josephson was awarded the Nobel Prize for this work in 1973. Until 1986, physicists had believed that the BCS theory forbade superconductivity at temperatures above about 30 K. That year, however, Johannes Bednorz and Karl Müller discovered superconductivity in a lanthanum-based cuprate perovskite material, which had a transition temperature of 35 K (Nobel Prize in Physics, 1987). It was soon found by Paul C. W. Chu of the University of Houston and M.K. Wu at the University of Alabama in Huntsville that replacing the lanthanum with yttrium (to make YBCO) raised the critical temperature to 92 K. This latter discovery was significant because liquid nitrogen could then be used as a refrigerant (at atmospheric pressure, the boiling point of nitrogen is 77 K). This is important commercially because liquid nitrogen can be produced cheaply on-site with no raw materials, and is not prone to some of the problems (such as solid air plugs) of liquid helium in piping. Many other cuprate superconductors have since been discovered, and the theory of superconductivity in these materials is one of the major outstanding challenges of theoretical condensed matter physics.

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Task №1 Answer the questions. 1. When was superconductivity discovered? 2. What kinds of properties are called superconductors? 3. What are superconductors used for? 4. Where does superconductivity occur? Who was awarded by the Nobel Prize in Physics in 1913? Task №2 Put in a/an or the where necessary. 1. In 1950, James Maxwell and Reynolds et al. found that ___ critical temperature of __superconductor depends on ___ isotopic mass of ___ constituent element. 2. In 1962 ___ first commercial superconducting wire, ___ niobium-titanium alloy, was developed by researchers at Westinghouse Electric Corporation. 3. Brian Josephson made ___ important theoretical prediction that ___ supercurrent can flow between two pieces of superconductor separated by __thin layer of insulator. 4. Josephson was awarded ___Nobel Prize for this work in 1973. 5. Johannes Bednorz and Karl Müller discovered superconductivity in __lanthanum-based cuprate perovskite material, which had __transition temperature of 35 K (Nobel Prize in Physics, 1987). Task №3 Put the verb into the correct form. 1. The electrical resistivity of a metallic conductor ____gradually as the temperature is lowered.( decrease) 2. The resistance of a superconductor, on the other hand, ___abruptly to zero when the material is cooled below a temperature called its «critical temperature». (drop) 3. Superconductivity _____in a wide variety of materials, including simple elements like tin and aluminum, various metallic alloys, and certain kinds of ceramic materials. (occur) 4. In 1986, the discovery of HTS, with critical temperatures in excess of 90 K, ____interest and research in superconductivity for several reasons. (renew) 5.The next important step in understanding superconductivity ____in 1933, when Walter Meissner and Robert Ochsenfeld ____ that superconductors ___magnetic fields.(occurr/discover/ apply) Task №4 Put the verb into the most suitable passive form. 1.Superconductivity ____ in 1911 by Heike Kamerlingh Onnes and _____by exactly zero electrical resistance and exclusion of the interior magnetic field. (discover/ characterize) 2. Superconductors ____to make some of the most powerful electromagnets known to man, including those used in MRI

Lesson 3 machines. (use) 3.They ___also ___to make digital circuits, highly sensitive magnetometers, and microwave filters for mobile phone base stations. (use) 4. They ___also for the separation of weakly magnetic particles from less magnetic or nonmagnetic particles. (can use) 5. Superconductivity does not occur in noble metals like gold and silver, nor in most metals that ___ spontaneously.(can/ magnetize). 6. Heike Kamerlingh Onnes ____the Nobel Prize in Physics in 1913. (award) Task №5 Put in a preposition where necessary. 1.Superconductivity was discovered __1911 __ Heike Kamerlingh Onnes, who was studying the resistance __ solid mercury __ cryogenic temperatures using the recently discovered liquid helium as a refrigerant. 2. ___1950 Lev Landau and Vitaly Ginzburg formulated what came to be called the phenomenological Ginzburg-Landau theory ___superconductivity. 3. The discovery revealed that the internal mechanism responsible ___ superconductivity was related __ the attractive force ____electrons and the ion lattice beneath. 4. The complete, microscopic theory ___ superconductivity was finally proposed ___ 1957 __John Bardeen (1908-1991), Leon Cooper, and John Schrieffer.5. ___ 1959 Lev Gor’kov showed that the BCS theory becomes equivalent ___ the Ginzburg-Landau theory close __ the critical temperature. Task №6 Put the verb into the correct form. Use gerund or the infinitive 1.____ future applications include high-performance transformers, power storage devices, electric power transmission, electric motors. (promise) 2. Superconductivity occurs in a wide variety of materials, _____simple elements like tin and aluminum, various metallic alloys, and certain kinds of ceramic materials known as high-temperature superconductors. ( include) 3. It ____be known as the BCS theory. (come) 4. This theory had great success in ____the macroscopic properties of superconductors. (explain) 5. Generalizations of these theories form the basis for____ the closely related phenomenon of superfluidity. (understand) Task №7 Put questions to the underlined words 1. Theory of superconductivity had a great success in explaining the macroscopic properties of superconductors. James Maxwell and Reynolds found that the critical temperature of a superconductor depends on the isotopic mass of the constituent element. Microscopic theory of superconductivity was finally proposed in 1957 by John Bardeen (1908-1991), Leon Cooper, and John Schrieffer.

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Introduction to the World of Physics In 1962 the first commercial superconducting wire, a niobium-titanium alloy, was developed by researchers at Westinghouse Electric Corporation. Physicists had believed that the BCS theory forbade superconductivity at temperatures above about 30 K.

LESSON 4 Active vocabulary Superconductors – Сверх­про­вод­ ни­ки resistivity удель­ное – соп­ро­тив­ле­ние magnetic field – маг­нит­ное по­ле heat capacity – теп­лоем­кос­ть critical temperature – кри­ти­чес­кая тем­пе­ра­ту­ра properties – свой­ст­ва particle accelerator – ус­ко­ри­тель час­тиц voltage – нап­ря­же­ние electric current – сверх­про­во­дя­щее сос­тоя­ние

superconducting state – элект­ри­ чес­кий ток current – ток coils – ка­туш­ки universe – все­лен­ная conductor – про­вод­ник ionic lattice – ион­ная ре­шет­ка vibrational kinetic energy – виб­ра­ ци­он­ная ки­не­ти­чес­кая энер­гия phenomenon – яв­ле­ние critical temperature – кри­ти­чес­кая тем­пе­ра­ту­ра fluid – жид­кость

Text 4 Elementary properties of superconductivity Superconductors possess both common and individual properties according to each kind. An example of a common property of superconductors is that they all have exactly zero resistivity to low applied currents when there is no magnetic field present. Individual properties include the heat capacity and the critical temperature at which superconductivity is destroyed. Most of the physical properties of superconductors vary from material to material, such as the heat capacity and the critical temperature above which superconductivity disappears. On the other hand, there is a class of properties that are independent of the underlying material.

Lesson 4

For instance, all superconductors have exactly zero resistivity to low applied currents when there is no magnetic field present. The existence of these “universal” properties implies that superconductivity is a thermodynamic phase and that these distinguishing properties are largely independent of microscopic details. Electric cables used by the European Organization for Nuclear Research (CERN). Regular cables (background) for 12,500 amps of electric current used at a particle accelerator called the Large ElectronPositron Collider (LEP); superconductive cable (foreground) for the same amount of electric current used at the Large Hadron Collider (LHC). The simplest method to measure the electrical resistance of a sample of some material is to place it in an electrical circuit in series with a current source “I” and measure the resulting voltage “U” across the sample. The resistance of the sample is given by Ohm’s law: . If the voltage is zero, then the resistance is zero, which means that the electric current is flowing freely through the sample and the sample is in its superconducting state. Superconductors are also able to maintain a current with no applied voltage whatsoever, a property exploited in superconducting electromagnets such as those found in MRI machines. Experiments have demonstrated that currents in superconducting coils can persist for years without any measurable degradation. Experimental evidence points to a current lifetime of at least 100,000 years, and theoretical estimates for the lifetime of persistent current exceed the lifetime of the universe. In a normal conductor, an electrical current may be visualized as a fluid of electrons moving across a heavy ionic lattice (the conducting material), consisting of atoms that are electrically neutral. The electrons are constantly colliding with the ions (electrically neutral atoms) in the lattice, and during each collision some of the energy carried by the current is absorbed by the lattice and converted into heat (which is essentially the vibrational kinetic energy, energy due to motion of the lattice ions). As a result, the energy carried by the current is constantly dissipated. This is the phenomenon of electrical resistance.

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In superconductors, on the other hand, the electronic fluid is not made up of individual electrons, but rather pairs of electrons called Cooper pairs, held together by an attractive force arising from the microscopic vibrations in the lattice. According to quantum mechanics, this Cooper pair fluid requires a minimum amount of energy, ∆E, for it to conduct an electrical current. Specifically, the energy supplied to the fluid needs to be greater than the thermal energy (temperature) of the lattice in order for superconductivity to appear. This is why superconductivity is achieved at extremely low temperatures. Superconducting phase transition In superconducting materials, the characteristics of superconductivity appear when the temperature T is lowered below a critical temperature Tc. The value of this critical temperature varies from material to material. Conventional superconductors usually have critical temperatures ranging from less than 1 K to around 20 K. Solid mercury, for example, has a critical temperature of 4.2 K. As of 2001, the highest critical temperature found for a conventional superconductor is 39 K for magnesium diboride (MgB2), although this material displays rather exotic properties that there is doubt about classifying it as a «conventional» superconductor. Cuprate superconductors can have much higher critical temperatures: YBCO (YBa2Cu3O7), one of the first cuprate (copper based) superconductors to be discovered, has a critical temperature of 92 K, and mercury-based cuprates have been found with critical temperatures in excess of 130 K. The explanation for these high critical temperatures remains unknown. The onset of superconductivity is accompanied by abrupt changes in various physical properties, which is the hallmark of a phase transition (when a material changes state, such as from solid to liquid). One such change, as seen above with the Cooper pairing, is that the electronic fluid in a normal conductor becomes a Cooper pair fluid in the superconducting state and this fluid also becomes a superfluid. Meissner effect When a superconductor is placed in a weak external magnetic field, the field penetrates the superconductor for only a short distance, called the penetration depth, after which it decays rapidly to zero. This is called the Meissner effect, and is a defining characteristic of

Lesson 4

superconductivity. For most superconductors, the penetration depth is on the order of 100 nanometers. The Meissner effect states that a superconductor expels all magnetic fields. Suppose we have a material in its normal state, containing a constant internal magnetic field. When the material is cooled below the critical temperature, we would observe the abrupt expulsion of the internal magnetic field. An equation (known as the London equation) predicts that the magnetic field in a superconductor decays exponentially from whatever value it possesses at the surface. The Meissner effect breaks down when the applied magnetic field is too large. Superconductors can be divided into two classes according to how this breakdown occurs. In Type I superconductors, superconductivity is abruptly lost when the strength of the applied field rises above a critical value. Depending on the geometry of the sample, one may obtain an intermediate state consisting of regions of normal material carrying a magnetic field mixed with regions of superconducting material containing no field. In Type II superconductors, raising the applied field past a critical value leads to a mixed state in which an increasing amount of magnetic flux (an amount of something that flows through a unit area in a unit time) penetrates the material, but there remains no resistance to the flow of electrical current as long as the current is not too large. At a second critical field strength, superconductivity is destroyed. Most pure elemental superconductors (except niobium, technetium, vanadium and carbon nanotubes) are Type I, while almost all impure and compound superconductors are Type II. Applications Superconductors are used to make some of the most powerful electromagnets known to man, including those used in MRI machines and the beam-steering magnets used in particle accelerators. They can also be used for magnetic separation, where weak magnetic particles are extracted from a background of less or non-magnetic particles, as in the pigment industries. Superconductors have also been used to make digital circuits and microwave filters for mobile phone base stations. Superconductors are used to build Josephson junctions, which are the building blocks of SQUIDs (superconducting quantum interference devices) – the most sensitive magnetometers known. Series

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of Josephson devices are used to define the SI volt. Depending on the particular mode of operation, a Josephson junction can be used as a photon detector or as mixer. The large resistance change at the transition from the normal- to the superconducting state is used to build thermometers in cryogenic micro-calorimeter photon detectors. Other early markets are arising where the relative efficiency, size, and weight advantages of devices based on high-temperature superconductors outweigh the additional costs involved. Promising future applications include high-performance transformers, power storage devices, electric power transmission, electric motors (such as for propulsion of vactrains or maglev trains), magnetic levitation devices, and fault current limiters. However, superconductivity is sensitive to moving magnetic fields, so applications that use alternating current (such as transformers) will be more difficult to develop than those that rely upon direct current. Superconductors in popular culture Superconductivity is a popular device in science fiction, due to the simplicity of the underlying concept – zero electrical resistance – and the rich technological possibilities. One of the first mentions of the phenomenon occurred in Robert A. Heinlein‘s novel Beyond This Horizon (1942). Notably, the use of a fictional room temperature superconductor was a major plot point in the Ringworld novels by Larry Niven, first published in 1970. Organic superconductors were featured in a science fiction novel by physicist Robert L. Forward. Also, superconducting magnets may be invoked to generate the powerful magnetic fields needed by Bussard ramjets, a type of spacecraft commonly encountered in science fiction. The most troublesome property of real superconductors, the need for cryogenic cooling, is often circumvented by postulating the existence of room temperature superconductors. Many stories attribute additional properties to their fictional superconductors, ranging from infinite heat (thermal) conductivity in Niven’s novels to providing power to an interstellar travel device in the Stargate movie and TV series (real superconductors conduct heat poorly, though superfluid helium has immense but finite heat conductivity).

Lesson 4

Task №1 Answer the questions. 1. What does the Large Electron-Positron Collider (LEP) mean? 2. What is the simplest method to measure the electrical resistance? 3. What are superconductors also able to maintain? 4. In what type is superconductivity abruptly lost when the strength of the applied field rises above a critical value? 5. Are superconductors used to make some of the most powerful electromagnets? Task №2 Put in a preposition where necessary. 1.Most ___ the physical properties ___ superconductors vary ___ material ___material, such as the heat capacity and the critical temperature ____ which superconductivity disappears. 2. Electric cables use ___ the European Organization ___ Nuclear Research (CERN). 3. Regular cables (background) ___ 12,500 amps ___ electric current used ___ a particle accelerator called the Large Electron-Positron Collider (LEP); superconductive cable (foreground) ___ the same amount ___ electric current used ___the Large Hadron Collider (LHC). 4. The energy supplied __ the fluid needs to be greater than the thermal energy (temperature) __the lattice in order for superconductivity __appear. Task №3 Complete the sentences with the relative clause: which, when. 1.An example of a common property of superconductors is that they all have exactly zero resistivity to low applied currents ___there is no magnetic field present. 2.Individual properties include the heat capacity and the critical temperature at ___ superconductivity is destroyed. 3.Most of the physical properties of superconductors vary from material to material, such as the heat capacity and the critical temperature above ___ superconductivity disappears. 4. If the voltage is zero, then the resistance is zero, ___means that the electric current is flowing freely through the sample and the sample is in its superconducting state. 5. In superconducting materials, the characteristics of superconductivity appear ___the temperature T is lowered below a critical temperature Tc. Task №4 Put in a/an or the where necessary. 1. ___simplest method to measure ___ electrical resistance of ___sample of some material is to place it in ___electrical circuit in series with ___current source «I» and measure the resulting voltage «U» across ___sample. 2. In __normal conductor, ___electrical current may be visualized as ___fluid

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Introduction to the World of Physics of electrons moving across __heavy ionic lattice (the conducting material), consisting of atoms that are electrically neutral. 3. When __ superconductor is placed in __ weak external magnetic field, ___ field penetrates ___ superconductor for only __ short distance, called ___penetration depth. 4. This is called ___ Meissner effect, and is ___defining characteristic of superconductivity. Task №5 Put the verb into the correct form. 1.Experiments ___ that currents in superconducting coils can persist for years without any measurable degradation. (demonstrate) 2. Experimental evidence ___to a current lifetime of at least 100,000 years, and theoretical estimates for the lifetime of persistent current exceed the lifetime of the universe. (point) 3.Conventional superconductors usually___ critical temperatures ranging from less than 1 K to around 20 K. (have) 4. The Meissner effect ___down when the applied magnetic field is too large. (break) 5. ___ Meissner effect states that ____superconductor expels all magnetic fields. Task №6 Complete the sentence. Use the comparative or superlative form. 1.____(simple) method to measure the electrical resistance of a sample of some material is to place it in an electrical circuit in series with a current source «I» and measure the resulting voltage «U» across the sample. 2. ___ (high) critical temperature found for a conventional superconductor is 39 K for magnesium diboride (MgB2). 3. ___ (troublesome) property of real superconductors, the need for cryogenic cooling, is often circumvented by postulating the existence of room temperature superconductors.4. Superconductors are used to build Josephson junctions, which are the building blocks of SQUIDs – ____ (sensitive) magnetometers known Task №7 Put questions to the underlined words 1. Individual properties include the heat capacity and the critical temperature at which superconductivity is destroyed. 2. All superconductors have exactly zero resistivity to low applied currents when there is no magnetic field present. 3. In superconducting materials, the characteristics of superconductivity appear when the temperature T is lowered below a critical temperature Tc. When a superconductor is placed in a weak external magnetic field, the field penetrates the superconductor for only a short distance, called the penetration depth, after which it decays rapidly to zero. At a second critical field strength, superconductivity is destroyed.

Lesson 5

LESSON 5 Active vocabulary Fullerene – фул­ле­рен, ба­ки­бол (мо­ле­ку­ла уг­ле­ро­да C2n в фор­ме по­ ло­го вы­пук­ло­го мно­гог­ран­ни­ка) Consist of – сос­тоять из Entirely – пол­ностью Resemble – на­по­ми­нать Allotrope – ал­лот­роп­ная мо­ди­фи­ ка­ция Similar – по­хо­жий Link – соеди­нять Derivative – преоб­ра­зо­ва­ние Carbon – уг­ле­род Trap – сх­ва­ты­вать Planar – плос­кий Superconductors – су­пер про­вод­ни­ки Appropriate – под­хо­дя­щий Discovery – отк­ры­тие Prediction – предс­ка­зы­ва­ние

Beam – луг Discrete – от­да­лен­ный Obtain – по­лу­чать Occurrence – появ­ле­ние Soot – ко­поть; са­жа Residue – ос­та­ток Lightning discharge – раз­ряд мол­нии Interstellar dust – кос­ми­чес­кая пыль Current – ток Purification – чис­то­та; очист­ка Layer – слой Reduce – умень­шать Property – свой­ст­во Resistance – соп­ро­тив­ле­ние Develop – раз­ви­вать Science fiction – фан­тас­ти­ка Armor – дос­пех Describe – опи­сы­вать

Text 5 Fullerenes Fullerenes are a family of carbon allotropes (other allotropes of carbon are graphite and diamond) consisting of molecules composed entirely of carbon atoms arranged in the form of hollow spheres, ellipsoids, or tubes. Each molecule generally has both pentagonal and hexagonal faces. The most common fullerene is Buckminsterfullerene, in which each molecule is composed of 60 carbon atoms that together take the shape of a soccer ball. It was named after Richard Buckminster Fuller, because its shape resembles Fuller’s design of a geodesic dome. By extension, spherical fullerenes are often called buckyballs, and cylindrical ones are called buckytubes, or, more accurately, carbon nanotubes. Fullerenes are similar in structure to graphite, which is composed of stacked sheets of linked hexagonal rings. In the case

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of a fullerene, however, the presence of pentagonal (or sometimes heptagonal) rings prevents its sheets from being planar. Chemists can now produce various derivatives of fullerenes. For example, hydrogen atoms, halogen atoms, or organic functional groups can be attached to fullerene molecules. Also, metal ions, noble gas atoms, or small molecules can be trapped in the cage-like structures of fullerene molecules, producing complexes that are known as endohedral fullerenes. If one or more carbon atoms in a fullerene molecule is replaced by metal atoms, the resultant compound is called a fulleride. Some doped fullerenes (doped with potassium or rubidium atoms, for example) are superconductors at relatively high temperatures Coining the name Buckminsterfullerene (C60) was named after Richard Buckminster Fuller, a noted architectural modeler who popularized the geodesic dome. Since buckminsterfullerenes have a similar shape to that sort of dome, the name was thought to be appropriate. As the discovery of the fullerene family came after buckminsterfullerene, the shortened name “fullerene” was used to refer to the family of fullerenes. Prediction and discovery In 1970, Eiji Osawa of Toyohashi University of Technology predicted the existence of C60 molecules. He noticed that the structure of a corannulene molecule was a subset of a soccer-ball shape, and he made the hypothesis that a full ball shape could also exist. His idea was reported in Japanese magazines, but did not reach Europe or America. In molecular beam experiments, discrete peaks were observed corresponding to molecules with the exact masses of 60, 70, or more of carbon atoms. In 1985, Harold Kroto (then at the University of Sussex), James R. Heath, Sean O’Brien, Robert Curl, and Richard Smalley, of Rice University, discovered C60, and shortly thereafter discovered other fullerenes. The first nanotubes were obtained in 1991. Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry for their roles in the discovery of this class of compounds. Natural occurrence and artificial production Minute quantities of the fullerenes–in the form of C60, C70, C76, and C84 molecules–have been found in soot and in the residue of carbon arc lamps. These molecules are also produced by lightning discharges

Lesson 5

in the atmosphere. Some analyses indicate that they are present in meteorites and interstellar dust. Recently, Buckminsterfullerenes were found in a family of minerals known as Shungites in Karelia, Russia. A common method used to produce fullerenes is to send a large current between two nearby graphite electrodes in an inert atmosphere. The resultant carbon plasma arc between the electrodes cools into sooty residue from which many fullerenes can be isolated. By 1991, it became relatively easy to produce gram-sized samples of fullerene powder using the techniques of Donald Huffman and Wolfgang Krätschmer. However, purification of fullerenes remains a challenge. Structural variations Since the discovery of fullerenes in 1985, a number of structural variations of fullerenes have been found. Examples include: – buckyball clusters: The smallest member is C20 (unsaturated version of dodecahedrane) and the most common is C60 – Nanotubes: Hollow tubes of very small dimensions, having single or multiple walls; potential applications in electronics industry – Megatubes: Larger in diameter than nanotubes and prepared with walls of different thickness; potentially used for the transport of a variety of molecules of different sizes – Polymers: Chain, two-dimensional and three-dimensional polymers are formed under high pressure high temperature conditions – Nano onions: Spherical particles based on multiple carbon layers surrounding a buckyball core; proposed for lubricant Fullerene rings[ Buckyballs

Buckminsterfullerene C60

A soccer ball is a model of the Buckminsterfullerene C60

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Carbon nanotubes Nanotubes are cylindrical fullerenes. These tubes of carbon are usually only a few nanometers wide, but they can range from less than a micrometer to several millimeters in length. They often have closed ends, but can be open-ended as well. There are also cases in which the tube reduces in diameter before closing off. Their unique molecular structure results in extraordinary macroscopic properties, including high tensile strength, high electrical conductivity, high ductility, high resistance to heat, and relative chemical inactivity (as it is cylindrical and «planar» – that is, it has no “exposed” atoms that can be easily displaced). One proposed use of carbon nanotubes is in paper batteries, developed in 2007 by researchers at Rensselaer Polytechnic Institute. Another proposed use in the field of space technologies and science fiction is to produce high-tensile carbon cables required by a space elevator. Properties In the past decade, the chemical and physical properties of fullerenes have been a hot topic in the field of research and development, and are likely to continue to be for a long time. Popular Science has published articles about the possible uses of fullerenes in armor. In April 2003, fullerenes were under study for potential medicinal use: Binding specific antibiotics to the structure to target resistant bacteria and even target certain cancer cells such as melanoma. The October 2005 issue of Chemistry and Biology contained an article describing the use of fullerenes as light-activated antimicrobial agents Task №1 Answer the questios. 1) Which faces does each molecule have according to the text? 2) What is the short name for buckminsterfullerene? 3) When were first nanotubes obtained? 4) Where have minute quantities of the fulleneres been found? 5) What is a common method used to produce fullerenes? Task №2 Put questions to the underlined words 1) The most common fullerene is Buckminsterfullerene.

Lesson 5 2) Fullerenes are similar in structure to graphite. 3) Some doped fullerenes are superconductors at relatively high temperature. 4) Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry for their roles in the discovery of this class of compounds. 5) Their unique molecular structure results in extraordinary macroscopic properties. Task №3 Match the following words with the correct definition according to the text 1) Nanotubes 2) Buckminsterfullerene 3) Fullerene 4) Buckyballs 5) Megatubes 6) Buckyball clusters 7) Nanotubes 8) Polymers 9) Nano onions a) are a family of carbon allotropes (other allotropes of carbon are graphite and diamond) consisting of molecules composed entirely of carbon atoms arranged in the form of hollow spheres, ellipsoids, or tubes. b) Cylindrical fullerenes c) Are cylindrical cylindrical d) Chain, two-dimensional and three-dimensional polymers are formed under high pressure high temperature conditions e) Spherical particles based on multiple carbon layers surrounding a buckyball core; proposed for lubricant f) The smallest member is C 20 (unsaturated version of dodecahedrane) and the most common is C 60 g) Larger in diameter than nanotubes and prepared with walls of different thickness; potentially used for the transport of a variety of molecules of different sizes h) Hollow tubes of very small dimensions, having single or multiple walls; potential applications in electronics industry i) The most common fullerene in which each molecule is composed of 60 carbon atoms that together take the shape of a soccer ball j) Are spherical fullerene Task №4 Find the equivalents to the following words in the text and make up sentences with them Completely, identical, prophesy, remind (of), connect, distant, receive, characteristic, decrease

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Introduction to the World of Physics Task №5 Give explanations for the following words: molecule, artificial production, atmosphere, Nobel prize, atom, science fiction, antibiotics, bacteria. Task № 6 Put definite or indefinite articles _ most common fullerene is Buckminsterfullerene, in which each molecule is composed of 60 carbon atoms that together take _ shape of _ soccer ball. It was named after Richard Buckminster Fuller, because its shape resembles Fuller’s design of _ geodesic dome. By extension, spherical fullerenes are often called buckyballs, and cylindrical ones are called buckytubes, or, more accurately, carbon nanotubes. Fullerenes are similar in structure to graphite, which is composed of stacked sheets of linked hexagonal rings. In _ case of _ fullerene, however, _ presence of pentagonal (or sometimes heptagonal) rings prevents its sheets from being planar. Task № 7 Put the words in brackets into the correct form Chemists can now (produce) various derivatives of fullerenes. For example, hydrogen atoms, halogen atoms, or organic functional groups can (attach) to fullerene molecules. Also, metal ions, noble gas atoms, or small molecules can (trap) in the cage-like structures of fullerene molecules, (produce) complexes that (know) as endohedral fullerenes. If one or more carbon atoms in a fullerene molecule (replace) by metal atoms, the resultant compound (call) a fulleride. Some doped fullerenes (doped with potassium or rubidium atoms, for example) (be) superconductors at relatively high temperatures.

LESSON 6 Active vocabulary Ubiquitous – вез­де­су­щий; пов­се­ ме­ст­ный unprecedented – бесп­ре­це­де­нтный, бесп­ри­мер­ный, не­бы­ва­лый retrospective – от­но­ся­щий­ся к прош­ло­му; ка­сающий­ся про­шед­ше­го alloy – сп­лав

chemistry – хи­мия century – век condense – уп­лот­нять, сгу­щать; умень­шать объём, сжи­мать behavior – по­ве­де­ние forefront – пе­ре­до­вая influence – влия­ние

Lesson 6 integral – су­ще­ст­вен­ный, неотъем­ ле­мый; пол­ный, це­лый fiber optic – во­ло­кон­но-оп­ти­чес­ кий interdisciplinary – меж­дис­цип­ли­ нар­ный

implant – внед­рять demand – тре­бо­ва­ние breakthrough – отк­ры­тие solutions – ре­ше­ние degradation – ухуд­ше­ние replacement – за­ме­на

Text 6 Materials science Materials science is an interdisciplinary field involving the study of different types of materials and the applications of knowledge about these materials to various areas of science and engineering. It combines elements of applied physics and chemistry, as well as chemical, mechanical, civil and electrical engineering. Materials science and materials engineering are often combined into a larger field of study. Materials used in early human history included metals, glasses, and clay-based ceramics. The past century has witnessed a surge in the development of new materials, including plastics, advanced ceramics, semiconductors, superconductors, liquid crystals, BoseEinstein condensates, and nanoscale substances, with a wide range of applications. Furthermore, materials science has grown to include testing these more exotic forms of condensed matter and developing new physics theories to explain their behavior. Consequently, materials science has been propelled to the forefront at many academic institutions and research facilities. Materials research at the basic level can lead to unprecedented influence on society. For example, semiconductor materials, which are ubiquitous in cars, telephones, computers, clocks, kitchen appliances, children’s toys, satellites, telescopes, and more, were a product of materials science research – into the electronic properties of the element germanium. Further research led to the replacement of germanium with the less costly silicon and to diverse approaches to modifying silicon’s properties by implanting other elements, such as phosphorous or boron, into the silicon matrix. Since their discovery in 1947, semiconductors have been steadily improved through materials

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science research driven by ever-increasing performance demands from the computer industry. Materials science is one of the oldest forms of applied science and engineering. In the history of human civilization, different eras have often been retrospectively identified according to an advance in the human ability to work with a new type of material. Examples are the Stone Age, Bronze Age, and Iron Age. A major breakthrough in the understanding of materials occurred in the late nineteenth century, when Willard Gibbs demonstrated that thermodynamic properties relating to atomic structure in various phases are related to the physical properties of a material. Before the 1960s, (and in some cases decades after), many materials science departments at academic and research institutions were named metallurgy departments, because the emphasis was on the study of metals and their uses. The field has since broadened to include every class of materials, such as ceramics, polymers, semiconductors, superconductors, superfluids, magnetic materials, medical implant materials, and biological materials. Many important elements of modern materials science have resulted from the space race. In particular, the understanding and engineering of metallic alloys, ceramics, and other materials were useful for the construction of space vehicles, space suits, and so forth, and the new knowledge was found valuable for various consumer and industrial applications as well. Materials science has laid the physical foundations of 21st century civilization, being integral to everything from fiber optic cables to tennis shoes, and from solar cells to sail boats. Materials science will continue to be centrally important in the quest for finding technological solutions toward sustainable development in the face of environmental degradation and the continued buildup of greenhouse gases due to the burning of carbon-based fuels. Task № 1 Answer the following questions 1) What is the materials science? 2) What elements does materials science combine? 3) What did materials used in early human history include? 4) Why has materials science been propelled to the forefront at many academic institutions and research facilities?

Lesson 6 5) What was the reason of the discovery of many important elements of modern materials science? Task № 2 Put questions to the underlined words 1. The past century has witnessed a surge in the development of new materials, including plastics, advanced ceramics, semiconductors, superconductors, etc. 2. Materials research at the basic level can lead to unprecedented influence on society. 3. Further research led to the replacement of germanium with the less costly silicon and to diverse approaches to modifying silicon’s properties by implanting other elements, such as phosphorous or boron, into the silicon matrix. 4. Since their discovery in 1947, semiconductors have been steadily improved through materials science research driven by ever-increasing performance demands from the computer industry. 5. A major breakthrough in the understanding of materials occurred in the late nineteenth century, when Willard Gibbs demonstrated that thermodynamic properties relating to atomic structure in various phases are related to the physical properties of a material. Task №3 Find the equivalents to the following words in the text and make up sentences with them For instance, ancient, include, university, investigation, period of time, appear. Task №4 Give explanations for the following words: applied physics, telescope, discovery, civilization, stone age, quest, environmental degradation, physical properties, greenhouse gases. Task № 5 Put definite or indefinite articles Materials science is one of _ oldest forms of applied science and engineering. In _ history of human civilization, different eras have often been retrospectively identified according to _ advance in _ human ability to work with _ new type of material. Examples are _ Stone Age, Bronze Age, and Iron Age. _ major breakthrough in _ understanding of materials occurred in _ late nineteenth century, when Willard Gibbs demonstrated that thermodynamic properties relating to atomic structure in various phases are related to _ physical properties of _ material.

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Introduction to the World of Physics Task № 6 Put words in brackets into the correct form Many important elements of modern materials science (result) from the space race. In particular, the understanding and engineering of metallic alloys, ceramics, and other materials (be) useful for the construction of space vehicles, space suits, and so forth, and the new knowledge (find) valuable for various consumer and industrial applications as well. Materials science (lay) the physical foundations of 21st century civilization, (be) integral to everything from fiber optic cables to tennis shoes, and from solar cells to sail boats. Materials science (continue) to be centrally important in the quest for (find) technological solutions toward sustainable development in the face of environmental degradation and the continued buildup of greenhouse gases due to the burning of carbon-based fuels.

LESSON 7 Active vocabulary Celestial body – не­бес­ное те­ло Tensile – рас­тя­жи­мый; элас­тич­ный Conventional – обыч­ный, обык­но­ вен­ный, тра­ди­ци­он­ный; Hazard – риск, опас­ность Anchored – надёжно зак­реп­лен­ный Tether – при­вязь Subset – подм­но­же­ст­во Skyhook – ан­тен­на; под­вес­ка Attain – дос­ти­гать, до­би­рать­ся Deploy – развёрты­ва­ние Feasible – реаль­ный, вы­пол­ни­мый, осу­ще­ст­ви­мый (о за­мыс­ле, пла­не и т. п.) Taper – плав­ный вол­но­вод­ный пе­ре­ход, заост­ре­ние (су­же­ние к краю, кон­цу) Centrifugal force – цент­ро­беж­ная си­ла Disturbance – бес­по­кой­ст­во, тре­во­ га; воз­буж­де­ние Payload – гру­зо­подъёмнос­ть ore – ру­да instantaneous velocity – мг­но­вен­ная ско­рос­ть

compile – вы­би­рать ин­фор­ма­цию, со­би­рать ма­те­ри­ал (из раз­ных ис­ точ­ни­ков) ribbon – лен­та, лен­точ­ка; тесь­ма shield – за­щи­та; за­щит­ное средс­тво oscillation – ка­ча­ние, рас­ка­чи­ва­ ние, ко­ле­ба­ние geostationary orbit – геос­та­цио­нар­ ная ор­би­та altitude – вы­со­та; вы­со­та над уров­нем мо­ря ascent – вос­хож­де­ние, подъём drag – тя­нуть, та­щить, во­ло­чить pendulum – маят­ник tilt – нак­лон, нак­лон­ное по­ло­же­ние efficiency – эф­фек­тив­нос­ть, ре­зуль­та­тив­ность, дей­ст­вен­ность dissipation – рас­сея­ние, рас­сеива­ние extraterrestrial – вне­зем­ной bulk – гру­да, ки­па; мас­са suspension – прио­станов­ка, пауза, пе­ре­рыв

Lesson 7

Text 7 A space elevator A space elevator is a proposed structure intended to transport material from the surface of a celestial body, particularly Earth, into space. Many variants have been proposed, all of which involve moving the material along a fixed structure instead of using rocket powered spacelaunch. The concept most often refers to a structure that reaches from the surface of the Earth to geostationary orbit (GSO) and a counter-mass beyond. Space elevators have also sometimes been referred to as beanstalks, space bridges, space lifts, space ladders, skyhooks, orbital towers, or orbital elevators. Recent discussions focus on tensile structures (tethers) reaching from geostationary orbit to the ground. (A tensile structure would be held in tension between Earth and the counterweight in space, like a guitar string held taut.) However, current technology is not capable of manufacturing practical materials that are sufficiently strong and light to build an Earth-based space elevator. This is because the total mass of conventional materials needed to construct such a structure would be far too great. Moreover, a space elevator would present a considerable navigational hazard for both aircraft and spacecraft. A space elevator would consist of a cable anchored to the Earth‘s surface, reaching into space. By attaching a counterweight at the end (or by further extending the cable for the same purpose), inertia ensures that the cable remains stretched taut, countering the gravitational pull on the lower sections, thus allowing the elevator to remain in geostationary orbit. Once beyond the gravitational midpoint, carriage would be accelerated further by the planet’s rotation. (Diagram not to scale.)

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Geostationary orbital tethers This concept, also called an orbital space elevator, geostationary orbital tether, or a beanstalk, is a subset of the skyhook concept, and is what people normally think of when the phrase ‘space elevator’ is used (although there are variants). Its construction would be a vast project: a tether would have to be built of a material that could endure tremendous stress while also being lightweight, cost-effective, and manufacturable in great quantities. Materials currently available do not meet these requirements, although carbon nanotube technology shows great promise. A considerable number of other novel engineering problems would also have to be solved to make a space elevator practical. Not all problems regarding feasibility have yet been addressed. Nevertheless, the LiftPort Group stated in 2002 that by developing the technology, the first space elevator could be operational by 2014. History The key concept of a space elevator dates back to 1895, when Russian scientist Konstantin Tsiolkovsky, proposed a compression structure (that is, a free-standing tower), or «Tsiolkovsky tower,» reaching from the surface of Earth to geostationary orbit. He was inspired by the Eiffel Tower in Paris to consider a tower that reached all the way into space, built from the ground up to an altitude of 35,790 kilometers above sea level (geostationary orbit). He noted that a «celestial castle» at the top of such a spindle-shaped cable would have the «castle» orbiting Earth in a geo stationary orbit (i.e. the castle would remain over the same spot on Earth’s surface). Tsiolkovsky’s tower would be able to launch objects into orbit without a rocket. Since the elevator would attain orbital velocity as it rode up the cable, an object released at the tower’s top would also have the orbital velocity necessary to remain in geostationary orbit. Unlike more recent concepts for space elevators, Tsiolkovsky’s (conceptual) tower was a compression structure, rather than a tension (or «tether») structure. Twentieth century Building a compression structure from the ground up proved an unrealistic task as there was no material in existence with enough compressive strength to support its own weight under such conditions.

Lesson 7

In 1959, another Russian scientist, Yuri N. Artsutanov, suggested a more feasible proposal. Artsutanov suggested using a geostationary satellite as the base from which to deploy the structure downward. By using a counterweight, a cable would be lowered from geostationary orbit to the surface of Earth, while the counterweight was extended from the satellite away from Earth, keeping the center of gravity of the cable motionless relative to Earth. Artsutanov’s idea was introduced to the Russian-speaking public in an interview published in the Sunday supplement of Komsomolskaya Pravda in 1960, but it was not available in English until much later. He also proposed tapering the cable thickness so that the tension in the cable was constant–this gives a thin cable at ground level, thickening up towards GSO. Making a cable over 35,000 kilometers long is a difficult task. In 1966, Isaacs, Vine, Bradner and Bachus, four American engineers, reinvented the concept, naming it a «Sky-Hook,» and published their analysis in the journal Science. They decided to determine what type of material would be required to build a space elevator, assuming it would be a straight cable with no variations in its cross section, and found that the strength required would be twice that of any existing material including graphite, quartz, and diamond. In 1975, American scientist Jerome Pearson reinvented the concept yet again, publishing his analysis in the journal Acta Astronautica. He designed a tapered cross section that would be better suited to building the elevator. The completed cable would be thickest at the geostationary orbit, where the tension was greatest, and would be narrowest at the tips to reduce the amount of weight per unit area of cross section that any point on the cable would have to bear. He suggested using a counterweight that would be slowly extended out to 144,000 kilometers (almost half the distance to the Moon) as the lower section of the elevator was built. Without a large counterweight, the upper portion of the cable would have to be longer than the lower due to the way gravitational and centrifugal forces change with distance from Earth. His analysis included disturbances such as the gravitation of the Moon, wind and moving payloads up and down the cable. The weight of the material needed to build the elevator would have required thousands of Space Shuttle trips, although part of the material could be transported up the elevator when a minimum strength strand reached the ground or be manufactured in space from asteroidal or lunar ore.

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In 1977, Hans Moravec published an article entitled «A NonSynchronous Orbital Skyhook,» in which he proposed an alternative space elevator concept, using a rotating cable, in which the rotation speed exactly matches the orbital speed in such a way that the instantaneous velocity at the point where the cable was at the closest point to the Earth was zero. This concept is an early version of a space tether transportation system. Twenty-first century After the development of carbon nanotubes in the 1990s, engineer David Smitherman of NASA/Marshall’s Advanced Projects Office realized that the high strength of these materials might make the concept of an orbital skyhook feasible, and organized a workshop at the Marshall Space Flight Center, inviting many scientists and engineers to discuss concepts and compile plans for an elevator turning the concept into a reality. The publication he edited compiling information from the workshop, «Space Elevators: An Advanced Earth-Space Infrastructure for the New Millennium» provides an introduction to the state of the technology at the time, and summarizes the findings. Another American scientist, Bradley C. Edwards, suggested creating a 100,000 km long paper-thin ribbon using a carbon nanotube composite material. He chose a ribbon type structure rather than a cable because that structure might stand a greater chance of surviving impacts by meteoroids. Supported by the NASA Institute for Advanced Concepts, the work of Edwards was expanded to cover the deployment scenario, climber design, power delivery system, orbital debris avoidance, anchor system, surviving atomic oxygen, avoiding lightning and hurricanes by locating the anchor in the western equatorial Pacific, construction costs, construction schedule, and environmental hazards. The largest holdup to Edwards’ proposed design is the technological limits of the tether material. His calculations call for a fiber composed of epoxy-bonded carbon nanotubes with a minimal tensile strength of 130 GPa (including a safety factor of 2); however, tests in 2000 of individual single-walled carbon nanotubes (SWCNTs), which should be notably stronger than an epoxy-bonded rope, indicated the strongest measured as 52 GPaMulti-walled carbon nanotubes were measured with tensile strengths up to 63 GPa.

Lesson 7

Climbers

Most space elevator designs call for a climber to move autonomously along a stationary cable. A space elevator cannot be an elevator in the typical sense (with moving cables) due to the need for the cable to be significantly wider at the center than the tips. While various designs employing moving cables have been proposed, most cable designs call for the «elevator» to climb up a stationary cable. Climbers cover a wide range of designs. On elevator designs whose cables are planar ribbons, most propose to use pairs of rollers to hold the cable with friction. Usually, elevators are designed for climbers to move only upwards, because that is where most of the payload goes. For returning payloads, atmospheric reentry on a heat shield is a very competitive option, which also avoids the problem of docking to the elevator in space. Climbers must be paced at optimal timings so as to minimize cable stress and oscillations and to maximize throughput. Lighter climbers can be sent up more often, with several going up at the same time. This increases throughput somewhat, but lowers the mass of each individual payload. As the car climbs, the elevator takes on a 1 degree lean, due to the top of the elevator traveling faster than the bottom around the Earth (Coriolis effect). This diagram is not to scale. The horizontal speed of each part of the cable increases with altitude, proportional to distance from the center of the Earth, reaching orbital velocity at geostationary orbit. Therefore as a payload is lifted up a space elevator, it needs to gain not only altitude but angular momentum (horizontal speed) as well. This angular momentum is taken

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from the Earth’s own rotation. As the climber ascends it is initially moving slightly more slowly than the cable that it moves onto (Coriolis effect) and thus the climber «drags» on the cable.

The overall effect of the centrifugal force acting on the cable causes it to constantly try to return to the energetically favorable vertical orientation, so after an object has been lifted on the cable the counterweight will swing back towards the vertical like an inverted pendulum. Provided that the Space Elevator is designed so that the center of weight always stays above geostationary orbit[29] for the maximum climb speed of the climbers, the elevator cannot fall over. Lift and descent operations must be carefully planned so as to keep the pendulum-like motion of the counterweight around the tether point under control. By the time the payload has reached GEO the angular momentum (horizontal speed) is enough that the payload is in orbit. The opposite process would occur for payloads descending the elevator, tilting the cable eastwards and insignificantly increasing Earth’s rotation speed. Powering climbers Both power and energy are significant issues for climbers- the climbers need to gain a large amount of potential energy as quickly as possible to clear the cable for the next payload.

Lesson 7

Nuclear energy and solar power have been proposed, but generating enough energy to reach the top of the elevator in any reasonable time without weighing too much is not feasible. The proposed method is laser power beaming, using megawatt powered free electron or solid state lasers in combination with adaptive mirrors approximately 10 m wide and a photovoltaic array on the climber tuned to the laser frequency for efficiency. A major obstacle for any climber design is the dissipation of the substantial amount of waste heat generated due to the less than perfect efficiency of any of the power methods. Nihon University professor engineering Yoshio Aoki, the director of the Japan Space Elevator Association, suggested including a second cable and using the superconductivity of carbon nanotubes to provide power. Counterweight There have been several methods proposed for dealing with the counterweight need: a heavy object, such as a captured asteroid or a space station, positioned past geostationary orbit, or extending the cable itself well past geostationary orbit. The latter idea has gained more support in recent years due to the relative simplicity of the task and the fact that a payload that went to the end of the counterweightcable would acquire considerable velocity relative to the Earth, allowing it to be launched into interplanetary space. Additionally, Brad Edwards proposed that initially elevators would be up-only, and that the elevator cars that are used to thicken up the cable could simply be parked at the top of the cable and act as a counterweight. Extraterrestrial elevators In principle, a space elevator might also be constructed on other planets, asteroids, and moons, which have weaker gravity than Earth. A Martian tether could be much shorter than one on Earth. Mars’ surface gravity is 38 percent of Earth’s, while it rotates around its axis in about the same time as Earth. Because of this, Martian areostationary orbit is much closer to the surface, and hence the elevator would be much shorter. Exotic materials might not be required to construct such an elevator. However, building a Martian elevator would be a unique challenge because the Martian moon Phobos is in a low

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orbit, and intersects the equator regularly (twice every orbital period of 11 h 6 min). A lunar space elevator can possibly be built with currently available technology about 50,000 kilometers long extending though the Earthmoon L1 point from an anchor point near the center of the visible part of Earth’s moon. On the far side of the moon, a lunar space elevator would need to be very long (more than twice the length of an Earth elevator) but due to the low gravity of the Moon, can be made of existing engineering materials. The construction of a space elevator would be a vast project requiring advances in engineering, manufacturing, and physical technology. One early plan involved lifting the entire mass of the elevator into geostationary orbit, and simultaneously lowering one cable downward towards the Earth’s surface while another cable is deployed upward directly away from the Earth’s surface. Alternatively, if nanotubes with sufficient strength could be made in bulk, a single hair-like 18-metric ton (20 short ton) ‘seed’ cable could be deployed in the traditional way, then progressively heavier cables would be pulled up from the ground along it, repeatedly strengthening it until the elevator reaches the required mass and strength. This is similar to the technique used to build suspension bridges. Task № 1 Answer the following questions 1) What are other names of space elevators? 2) Why did Konstantin Tsilkovsky consider a tower that reached all the way into space? 3) Where did an American scientist publish his analysis? 4) Why cannot a space elevator be an elevator in its typical sense? 5) Where climbers must be paced so as to minimize cable stress and oscillations and to maximize throughput? 6) How does the horizontal speed of each part of the cable increase? 7) Is it possible to construct a space elevator on other planets? Task № 2 Make questions to the underlined word 1. A space elevator is a proposed structure intended to transport material from the surface of a celestial body, particularly Earth, into space. 2. Recent discussions focus on tensile structures (tethers) reaching from geostationary orbit to the ground.

Lesson 7 3. The key concept of a space elevator dates back to 1895. 4. Tsiolkovsky’s tower would be able to launch objects into orbit without a rocket. 5. Building a compression structure from the ground up proved an unrealistic task as there was no material in existence with enough compressive strength to support its own weight under such conditions. 6. American scientist Jerome Pearson designed a tapered cross section that would be better suited to building the elevator. 7. Nuclear energy and solar power have been proposed, but generating enough energy to reach the top of the elevator in any reasonable time without weighing too much is not feasible. Task №3 Find the equivalents to the following words in the text and make up sentences with them Real, height, accomplishable, slope, risk, elastic, traditional, reach, armor, pause. Task №4 Match the following words with the correct definition 1) space elevator 2) tether  3) spacecraft  4) geosynchronous orbit 5) counterweight  6) Eiffel Tower 7) Moon  8) Asteroids 9) angular momentum 10) space station a) are minor planets, especially those of the inner Solar system. The larger ones have also been called planetoids.  b) is a vehicle, vessel or machine designed to fly in outer space.  c)  is a measure of the amount of rotation an object has, taking into account its mass, shape and speed. d) is a proposed type of space transportation system. e) is a spacecraft capable of supporting a crew, which is designed to remain in space (most commonly in low Earth orbit) for an extended period of time and for other spacecraft to dock. is an orbit around the Earth with an orbital period of one sidereal day, intentionally matching the Earth’s sidereal rotation period (approximately 23 hours 56 minutes and 4 seconds).[

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Introduction to the World of Physics is Earth’s only natural satellite. is a cord, fixture, or flexible attachment that anchors something movable to a reference point which may be fixed or moving.  is an iron lattice tower located on the Champ de Mars in Paris. is an equivalent counterbalancing weight that balances a load Task №5 Give explanations for the following words: energy, power, space station, orbit, instantaneous speed, suspension bridge, spacecraft, rocket, satellite, asteroid, counterweight, superconductivity, centrifugal force. Task №6 Put definite or indefinite articles Its construction would be _ vast project: _ tether would have to be built of _ material that could endure tremendous stress while also being lightweight, cost-effective, and manufacturable in great quantities. Materials currently available do not meet these requirements, although carbon nanotube technology shows great promise. _ considerable number of other novel engineering problems would also have to be solved to make _ space elevator practical. Not all problems regarding feasibility have yet been addressed. Nevertheless, _ LiftPort Group stated in 2002 that by developing _ technology, _ first space elevator could be operational by 2014. Task № 7 Put the given words in brackets into the correct form (Build) a compression structure from the ground up (prove) an unrealistic task as there (be) no material in existence with enough compressive strength to (support) its own weight under such conditions. In 1959, another Russian scientist, Yuri N. Artsutanov, (suggest) a more feasible proposal. Artsutanov (suggest) (use) a geostationary satellite as the base from which to (deploy) the structure downward. By (use) a counterweight, a cable would (lower) from geostationary orbit to the surface of Earth, while the counterweight (extend) from the satellite away from Earth, (keep) the center of gravity of the cable motionless relative to Earth. Artsutanov’s idea (introduce) to the Russian-speaking public in an interview (publish) in the Sunday supplement of Komsomolskaya Pravda in 1960, but it (be not) available in English until much later. He also (propose) (taper) the cable thickness so that the tension in the cable (be) constant–this (give) a thin cable at ground level, (thicken) up towards GSO.

Lesson 8

LESSON 8 Active vocabulary Demolition – раз­ру­ше­ние; раз­бор­ ка, снос Arbitrarily – без дос­та­точ­ных ос­ но­ва­ний, произ­воль­но; свое­воль­но Stretch – рас­тя­ги­вать Compress – сжи­мать Bungee – пру­жин­ное уст­рой­ст­во Harness – обуз­ды­вать, по­ко­рять (ре­ку и т.п.) ; ис­поль­зо­вать Wrecking – сне­се­ние, снос, де­мон­ таж (зда­ний) Blade – лез­вие, кли­нок; по­лот­ни­ще (пи­лы) Subsequently – впос­ледст­вии, за­ тем, по­том

Magnitude – ве­ли­чи­на, раз­ме­ры Instantaneous – мг­но­вен­ный; не­ мед­лен­ный, не­за­мед­ли­тель­ный Tangential – нап­рав­лен­ный по ка­ са­тель­ной к дан­ной кри­вой Acceleration – ус­ко­ре­ние, убыст­ре­ ние; ак­се­ле­ра­ция Inward – внут­рен­ний, на­хо­дя­щий­ ся внут­ри Centripetal force – цент­ро­беж­ная си­ла Sturdy – проч­ный, креп­кий Store – хра­нить Earth – Зем­ля Height – вы­со­та Force – си­ла

Text 8 Potential energy An object can store energy as the result of its position. For example, the heavy ball of a demolition machine is storing energy when it is held at an elevated position. This stored energy of position is referred to as potential energy. Similarly, a drawn bow is able to store energy as the result of its

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position. When assuming its usual position (i.e. when not drawn), there is no energy stored in the bow. Yet when its position is altered from its usual equilibrium position, the bow is able to store energy by virtue of its position. This stored energy of position is referred to as potential energy. Potential energy is the stored energy of position possessed by an object. Gravitational Potential Energy The two examples above illustrate the two forms of potential energy – gravitational potential energy and elastic potential energy. Gravitational potential energy is the energy stored in an object as the result of its vertical position or height. The energy is stored as the result of the gravitational attraction of the Earth on the object. The gravitational potential energy of the massive ball of a demolition machine is dependent on two variables – the mass of the ball and the height to which it is raised. There is a direct relation between gravitational potential energy and the mass of an object. More massive objects have greater gravitational potential energy. There is also a direct relation between gravitational potential energy and the height of an object. The higher an object is elevated, the greater the gravitational potential energy. To determine the gravitational potential energy of an object, a zero height position must first be arbitrarily assigned. Typically, the ground is considered to be a position of zero height. But this is merely an arbitrarily assigned position that most people agree upon. Since many of our labs are done on tabletops, it is often customary to assign the tabletop to be the zero height position. Again this is merely arbitrary. If the tabletop is the zero position, then the potential energy of an object is based upon its height relative to the tabletop. For

Lesson 8

example, a pendulum bob swinging to and from above the tabletop has a potential energy that can be measured based on its height above the tabletop. By measuring the mass of the bob and the height of the bob above the tabletop, the potential energy of the bob can be determined. Elastic Potential Energy The second form of potential energy that we will discuss is elastic potential energy. Elastic potential energy is the energy stored in elastic materials as the result of their stretching or compressing. Elastic potential energy can be stored in rubber bands, bungee chords, trampolines, springs, an arrow drawn into a bow, etc. The amount of elastic potential energy stored in such a device is related to the amount of stretch of the device – the more the stretch, the more the stored energy. Springs are a special case of a device that can store elastic potential energy due to either compression or stretching. A force is required to compress a spring; the more compression there is, the more force is required to compress it further. For certain springs, the amount of force is directly proportional to the amount of stretch or compression (x); the constant of proportionality is known as the spring constant (k). Fspring = k • x Such springs are said to follow Hooke’s Law. If a spring is not stretched or compressed, there is no elastic potential energy stored in it. The spring is said to be at its equilibrium position. The equilibrium position is the position that the spring naturally assumes when there is no force applied to it. In terms of potential energy, the equilibrium position could be called the zero-potential energy position. There is a special equation for springs that relates the amount of elastic potential energy to the amount of stretch (or compression) and the spring constant.

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Mechanical Energy as the Ability to Do Work An object that possesses mechanical energy is able to do work. In fact, mechanical energy is often defined as the ability to do work. Any object that possesses mechanical energy – whether it is in the form of potential energy or kinetic energy – is able to do work. That is, its mechanical energy enables that object to apply a force to another object in order to cause it to be displaced. Numerous examples can be given of how an object with mechanical energy can harness that energy in order to apply a force to cause another object to be displaced. A classic example involves the massive wrecking ball of a demolition machine. The wrecking ball is a massive object that is swung backwards to a high position and allowed to swing forward into building structure or other object in order to demolish it. Upon hitting the structure, the wrecking ball applies a force to it in order to cause the wall of the structure to be displaced. The diagram below depicts the process by which the mechanical energy of a wrecking ball can be used to do work.

The massive ball of a demolition machine possesses mechanical energy – the ability to do work. When held at a height, it possesses mechanical energy in the form of potential energy. As it falls, it exhibits mechanical energy in the form of kinetic energy. As it strikes the structure to be demolished, it applies a force to displace the structure – i.e., it does work upon the structure.

A hammer is a tool that utilizes mechanical energy to do work. The mechanical energy of a hammer gives the hammer its ability to apply a force to a nail in order to cause it to be displaced. Because the hammer has mechanical energy (in the form of kinetic energy), it is able to do work on the nail. Mechanical energy is the ability to do work.

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Another example that illustrates how mechanical energy is the ability of an object to do work can be seen any evening at your local bowling alley. The mechanical energy of a bowling ball gives the ball the ability to apply a force to a bowling pin in order to cause it to be displaced. Because the massive ball has mechanical energy (in the form of kinetic energy), it is able to do work on the pin. Mechanical energy is the ability to do work. A common scene in some parts of the countryside is a “wind farm.” High-speed winds are used to do work on the blades of a turbine at the socalled wind farm. The mechanical energy of the moving air gives the air particles the ability to apply a force and cause a displacement of the blades. As the blades spin, their energy is subsequently converted into electrical energy (a non-mechanical form of energy) and supplied to homes and industries in order to run electrical appliances. Because the moving wind has mechanical energy (in the form of kinetic energy), it is able to do work on the blades. Once more, mechanical energy is the ability to do work. The Total Mechanical Energy As already mentioned, the mechanical energy of an object can be the result of its motion (i.e., kinetic energy) and/or the result of its stored energy of position (i.e., potential energy). The total amount of mechanical energy is merely the sum of the potential energy and the kinetic energy. This sum is simply referred to as the total mechanical energy (abbreviated TME). TME = PE + KE As discussed earlier, there are two forms of potential energy discussed in our course – gravitational potential energy and elastic potential energy. Given this fact, the above equation can be rewritten: TME = PEgrav + PEspring + KE

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The Direction of the Velocity Vector Objects moving in uniform circular motion will have a constant speed. But does this mean that they will have a constant velocity? Speed is a scalar quantity and velocity is a vector quantity. Velocity, being a vector, has both a magnitude and a direction. The magnitude of the velocity vector is the instantaneous speed of the object. The direction of the velocity vector is directed in the same direction that the object moves. Since an object is moving in a circle, its direction is continuously changing. At one moment, the object is moving northward such that the velocity vector is directed northward. One quarter of a cycle later, the object would be moving eastward such that the velocity vector is directed eastward. As the object rounds the circle, the direction of the velocity vector is different from that it was the instant before. So while the magnitude of the velocity vector may be constant, the direction of the velocity vector is changing. The best word that can be used to describe the direction of the velocity vector is the word tangential. The direction of the velocity vector at any instant is in the direction of a tangent line drawn to the circle at the object’s location. (A tangent line is a line that touches a circle at one point but does not intersect it.) The diagram at the right shows the direction of the velocity vector at four different points for an object moving in a clockwise direction around a circle. While the actual direction of the object (and thus, of the velocity vector) is changing, its direction is always tangent to the circle. To summarize, an object moving in uniform circular motion is moving around the perimeter of the circle at a constant speed. While the speed of the object is constant, its velocity is changing. Velocity, being a vector, has a constant magnitude but a changing direction. The direction is always directed tangent to the circle and as the object turns the circle, the tangent line is always pointing in a new direction. An object moving in a circle is experiencing an acceleration. Even if moving around the perimeter of the circle at a constant speed, there is still a change in velocity and subsequently an acceleration. This acceleration is directed towards the center of the circle. In accordance with Newton’s second law of motion, an object, which experiences

Lesson 8

acceleration, must also experience a net force. The direction of the net force is in the same direction as that of the the acceleration. So, for an object moving in a circle, there must be an inward force acting upon it in order to cause its inward acceleration. This is sometimes referred to as the centripetal force requirement. The word centripetal (not to be confused with the F-word centrifugal) means center seeking. For the object moving in circular motion, there is a net force acting towards the center which causes the object to seek the center. To understand the importance of a centripetal force, it is important to have a sturdy understanding of the Newton’s first law of motion – the law of inertia. The law of inertia states that ...... objects in motion tend to stay in motion at the same speed and the same direction unless acted upon by an unbalanced force. According to Newton’s first law of motion, there is a natural tendency of all moving objects to continue motion in the same direction that they are moving ... unless some form of unbalanced force acts upon the object to deviate its motion from its straight-line path. Moving objects will tend to naturally travel in straight lines; an unbalanced force is only required to cause it to turn. Thus, the presence of an unbalanced force is required for objects to move in circles. Inertia, Force and Acceleration for an Automobile Passenger The idea expressed by Newton’s law of inertia should not be surprising to us. We experience this phenomenon of inertia nearly every day when we drive our automobile. For example, imagine that you are a passenger in a car at a traffic light. The light turns green and the driver accelerates from rest. The car begins to accelerate forward, yet relative to the seat you are on your body begins to lean backwards. Your body being at rest tends to stay at rest. This is one aspect of the law of inertia – “objects at rest tend to stay at rest.” As the wheels of the car spin to generate a forward force upon the car and cause a forward acceleration, your body tends to stay in place. It certainly might seem to you as though your body were experiencing a backward force causing it to accelerate backwards. Yet you would have a difficult time identifying such a backward force on your body. Indeed, there isn’t one. The feeling of being thrown backwards is merely the tendency of your body to resist the acceleration and to remain in its state of rest. The car is accelerating out from under your body, leaving you with the false feeling of being pushed backwards.

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Now imagine that you are in the same car moving along at a constant speed approaching a stoplight. The driver applies the brakes, the wheels of the car lock, and the car begins to skid to a stop. There is a backward force upon the forward moving car and subsequently a backward acceleration on the car. However, your body, being in motion, tends to continue motion while the car is skidding to a stop. It certainly might seem to you as though your body were experiencing a forward force causing it to accelerate forward. Indeed, there is no physical object accelerating you forward. The feeling of being thrown forwards is merely the tendency of your body to resist the deceleration and to remain in its state of forward motion. This is the second aspect of Newton’s law of inertia – “an object in motion tends to stay in motion at the same speed and in the same direction... .” The unbalanced force acting upon the car causes the car to slow down while your body continues its forward motion. You are once more left with the false feeling of being pushed in a direction, which is opposite to your acceleration. The tendency of a passenger’s body to maintain its state of rest or motion while the surroundings (the car) accelerate is often misconstrued as an acceleration. This becomes particularly problematic when we consider the third possible inertia experience of a passenger in a moving automobile – the left hand turn. Suppose that on the next part of your travels the driver of the car makes a sharp turn to the left at a constant speed. During the turn, the car travels in a circulartype path. That is, the car sweeps out one-quarter of a circle. The friction force acting upon the turned wheels of the car causes an unbalanced force upon the car and a subsequent acceleration. The unbalanced force and the acceleration are both directed towards the center of the circle about which the car is turning. Your body however is in motion and tends to stay in motion. It is the inertia of your body – the tendency to resist acceleration – that causes it to continue in its

Lesson 8

forward motion. While the car is accelerating inward, you continue in a straight line. If you are sitting on the passenger side of the car, then eventually the outside door of the car will hit you as the car turns inward. This phenomenon might cause you to think that you are being accelerated outwards away from the center of the circle. In reality, you are continuing in your straight-line inertial path tangent to the circle while the car is accelerating out from under you. The sensation of an outward force and an outward acceleration is a false sensation. There is no physical object capable of pushing you outwards. You are merely experiencing the tendency of your body to continue in its path tangent to the circular path along which the car is turning. You are once more left with the false feeling of being pushed in a direction that is opposite to your acceleration. Any object moving in a circle (or along a circular path) experiences a centripetal force. That is, there is some physical force pushing or pulling the object towards the center of the circle. This is the centripetal force requirement. The word centripetal is merely an adjective used to describe the direction of the force. We are not introducing a new type of force but rather describing the direction of the net force acting upon the object that moves in the circle. Whatever the object, if it moves in a circle, there is some force acting upon it to cause it to deviate from its straight-line path, accelerate inwards and move along a circular path. Task №1 Answer the following questions 1) What is a potential energy? 2) What does potential energy depend on? 3) What are two types of potential energy? 4) Is there any potential energy stored in a spring if it is not stretched or compressed? 5) What is mechanical energy? Task №2 Make questions to the underlined word 1) The wrecking ball is a massive object that is swung backwards to a high position and allowed to swing forward into building structure or other object in order to demolish it. 2) The mechanical energy of a hammer gives the hammer its ability to apply a force to a nail in order to cause it to be displaced.

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Introduction to the World of Physics 3) Because the hammer has mechanical energy (in the form of kinetic energy), it is able to do work on the nail. 4) High-speed winds are used to do work on the blades of a turbine at the so-called wind farm. 5) There are two forms of potential energy. 6) Objects moving in uniform circular motion will have a constant speed. 7) Velocity, being a vector, has both a magnitude and a direction. 8) The direction of the velocity vector is directed in the same direction that the object moves. Task №3 Find the equivalents to the following words in the text and make up sentences with them Shrink, momentary, lengthen, interior, altitude, keep, strong, size, use Task №4 Match the following words with the correct definition 1) potential energy 2) mechanical energy 3) scalar  4) Acceleration 5) Elastic energy 6) circular motion 7) Centripetal force 8) Inertia  a) is the potential mechanical energy stored in the configuration of a material or physical system as work is performed to distort its volume or shape. b)  is a one-dimensional physical quantity, i.e. one that can be described by a single real number (sometimes signed, often with units), unlike (or as a special case of) vectors, tensors, etc. which are described by several numbers which characterize magnitude and direction.  c) is the energy stored in an object due to its position in a force field or in a system due to its configuration. d)  is the resistance of any physical object to any change in its state of motion, including changes to its speed and direction.  e) is a force that makes a body follow a curved path. f) is the rate at which the velocity of an object changes over time.  g)  is the sum of potential energy and kinetic energy. h) is a movement of an object along the circumference of a circle or rotation along a circular path.  Task №5 Give explanations for the following words: mechanical energy, demolition machine, elastic energy, resistance, velocity, speed, work, direction.

Lesson 9 Task №6 Put definite or indefinite articles To determine __ gravitational potential energy of _ object, _ zero height position must first be arbitrarily assigned. Typically, __ ground is considered to be _ position of zero height. But this is merely __ arbitrarily assigned position that most people agree upon. Since many of our labs are done on tabletops, it is often customary to assign __ tabletop to be _ zero height position. Again this is merely arbitrary. If __ tabletop is _ zero position, then _ potential energy of _ object is based upon its height relative to __ tabletop. For example, _ pendulum bob swinging to and from above _ tabletop has _ potential energy that can be measured based on its height above _ tabletop. By measuring _ mass of _ bob and _ height of _ bob above _ tabletop, _ potential energy of _ bob can be determined. Task №7 Put the given words in brackets into the correct form The second form of potential energy that we (discuss) (be) elastic potential energy. Elastic potential energy (be) the energy stored in elastic materials as the result of their stretching or compressing. Elastic potential energy can (store) in rubber bands, bungee chords, trampolines, springs, an arrow (draw) into a bow, etc. The amount of elastic potential energy (store) in such a device (be) (relate) to the amount of stretch of the device – the more the stretch, the more the stored energy.

LESSON 9 Active vocabulary Countertop – ра­бо­чая по­ве­рх­нос­ть Purposes – об­суж­де­ние Surroundings – ок­ру­же­ние Gradually – пос­те­пен­но cool down – ос­тыть drinkable – питьевой macroscopic – мак­рос­ко­пи­чес­кий surroundings – ок­ру­жающая сре­да lowers – сни­жает particles – час­тиц decreasing – умень­шает­ся consider – расс­мот­реть escaping – спа­саясь

leaking – про­те­кая heat transfer – пе­ре­да­ча теп­ла increase – уве­ли­че­ние summarized – ре­зю­ми­ро­вать statements – заяв­ле­ния releasing – вы­пус­тив gaining – по­лу­чать convincing – убе­ди­тель­но proof – до­ка­за­тель­ст­во large – мно­го negligibly – пре­неб­ре­жи­мо abnormally – не­нор­мально noticeable – за­мет­но

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Text 9 What is Heat? Consider a very hot mug of coffee on the countertop of your kitchen. For discussion purposes, we will say that the cup of coffee has a temperature of 80°C and that the surroundings (countertop, air in the kitchen, etc.) have a temperature of 26°C. What do you suppose will happen in this situation? I suspect that you know that the cup of coffee will gradually cool down over time. At 80°C, you wouldn’t dare to drink the coffee. Even the coffee mug will likely be too hot to touch. But over time, both the coffee mug and the coffee will cool down. Soon it will be at a drinkable temperature. And if you resist the temptation to drink the coffee, it will eventually reach room temperature. The coffee cools from 80°C to about 26°C. So what is happening over the course of time to cause the coffee to cool down? The answer to this question can be both macroscopic and particulate in nature. On the macroscopic level, we would say that the coffee and the mug are transferring heat to the surroundings. This transfer of heat occurs from the hot coffee and hot mug to the surrounding air. The fact that the coffee lowers its temperature is a sign that the average kinetic energy of its particles is decreasing. The coffee is losing energy. The mug is also lowering its temperature; the average kinetic energy of its particles is also decreasing. The mug is also losing energy. The energy that is lost by the coffee and the mug is transferred to the colder surroundings. We refer to this transfer of energy from the coffee and the mug to the surrounding air and countertop as heat. In this sense, heat is simply the transfer of energy from a hot object to a colder object. Now let’s consider a different scenario – a cold can of pop placed on the same kitchen counter. For discussion purposes, we will say that the pop and the can which contains it has a temperature of 5°C and that the surroundings (countertop, air in the kitchen, etc.) have a temperature of 26°C. What will happen to the cold can of pop over the course of time? The cold pop and the container will both warm up to room temperature. But what is happening to cause these colder-thanroom-temperature objects to increase their temperature? Is the cold escaping from the pop and its container? No! There is no such thing as the cold escaping or leaking. Rather, our explanation is very similar to the explanation used to explain why the coffee cools down. There is a heat transfer.

Lesson 9

Over time, the pop and the container increase their temperature. The temperature rises from 5°C to nearly 26°C. This increase in temperature is a sign that the average kinetic energy of the particles within the pop and the container is increasing. In order for the particles within the pop and the container to increase their kinetic energy, they must be gaining energy from somewhere. But from where? Energy is being transferred from the surroundings (countertop, air in the kitchen, etc.) in the form of heat. Just as in the case of the cooling coffee mug, energy is transferred from the higher temperature objects to the lower temperature object. Both of these scenarios could be summarized by two simple statements. An object decreases its temperature by releasing energy in the form of heat to its surroundings. And an object increases its temperature by gaining energy in the form of heat from its surroundings. Both the warming up and the cooling down of objects works in the same way – by heat transfer from the higher temperature object to the lower temperature object. So now we can meaningfully restate the definition of temperature. Temperature is a measure of ability of a substance, or more generally of any physical system, to transfer heat energy to another physical system. The higher the temperature of an object is, the greater the tendency of that object to transfer heat. The lower the temperature of an object is, the greater the tendency of that object to be on the receiving end of the heat transfer. But perhaps you have been asking: what happens to the temperature of surroundings? Do the countertop and the air in the kitchen increase their temperature when the mug and the coffee cool down? And do the countertop and the air in the kitchen decrease their temperature when the can and its pop warm up? The answer is a resounding Yes! The proof? Just touch the countertop – it should feel cooler or warmer than before the coffee mug or pop can were placed on the countertop. But what about the air in the kitchen? Now that’s a little more difficult to present a convincing proof of. The fact that the volume of air in the room is so large and that the energy quickly diffuses away from the surface of the mug means that the temperature change of the air in the kitchen will be abnormally small. In fact, it will be negligibly small. There would have to be a lot more heat transfer before there is a noticeable temperature change.  

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Task №1 Answer the questions 1) How many degrees in coffee are there of room temperature? 2) What is a heat transfer? 3) How is energy transferred? 4) What is the temperature of the boiling water? 5) What happens to the temperature of surroundings? Task №2 Make questions to the underlined words 1) A temperature is a comparative objective measure of hot and cold. 2) The coffee is losing energy. 3) An object decreases its temperature by releasing energy in the form of heat to its surroundings. 4) On the macroscopic level, we would say that the coffee and the mug are transferring heat to the surroundings. Task №3 Match the following words with the correct definitions according to the text 1) Heat (a) 2) Energy (c) 3) Temperature (e) 4) Air (b) 5) Warm (f) 6) Heat transfer (g) 7) Surroundings (d) a) is the transfer of energy other than by work or transfer of matter b) Natural mix of gases forming the atmosphere. c) is a property of objects, transferable among them via fundamental interactions, which can be converted in form but not created or destroyed. d) are the area around a given physical or geographical point or place e) is a comparative objective measure of hot and cold. f) A somewhat high temperature g) describes the exchange of thermal energy, between physical systems depending on the temperature and pressure, by dissipating heat Task №4 Find the equivalents to the following words in the text and make up sentences with them: Cup, extension, maybe, small, environment, wrong, feeling, finally. Task №5 Give explanations for the following words: warming up, negligibly, cooling down, atmosphere, kinetic.

Lesson 10 Task № 6 True or false? 1) The coffee cools from 80°C to about 26°C. 2) An object decreases its temperature by releasing energy in the form of heat to its surroundings. 3) Energy is being transferred from the objects 4) The higher the temperature of an object is, the greater the tendency of that object to transfer heat 5) There would not have to be a heat transfer before there is a noticeable temperature change.

LESSON 10 Active vocabulary Degree-сте­пень Environment-сре­да Measure-ме­ра Substance-ве­ще­ст­во Terms-еди­ни­цы Designated-оп­ре­де­ляемый Various-раз­лич­ный Furthered-спо­со­бс­тво­вать Accurate-точ­ный Sophisticated-слож­ный Familiar-зна­ко­мый Liquid-жид­кость Mercury-ртуть Expansion-рас­ши­ре­ние

Volume-объем Nearly-прак­ти­чес­ки Exhibit-де­мо­нс­три­руют Increases-воз­рас­тает Enclosed-зак­лю­че­на cross-sectional -по­пе­реч­но­го се­че­ ния cause-при­чи­на calibration-ка­либ­ров­ка placement-раз­ме­ще­ние freezing-за­мо­ра­жи­ваясь height-вы­со­та relationship-за­ви­си­мос­ть

Text 10 What is Temperature? Despite our built-in feel for temperature, it remains one of those concepts in science that is difficult to define. Here are some of those definitions of temperature:

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– The degree of hotness or coldness of a body or environment. – A measure of the warmth or coldness of an object or substance with reference to some standard value. – A measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale. – A measure of the ability of a substance, or more generally of any physical system, to transfer heat energy to another physical system. – Any of various standardized numerical measures of this ability, such as the Kelvin, Fahrenheit, and Celsius scale. For certain, we are comfortable with the first two definitions – the degree or measure of how hot or cold an object is. But our understanding of temperature is not furthered by such definitions. The third and the fourth definitions that reference the kinetic energy of particles and the ability of a substance to transfer heat are scientifically accurate. However, these definitions are far too sophisticated to serve as good starting points for a discussion of temperature. So we will resign to a definition similar to the fifth one that is listed – temperature can be defined as the reading on a thermometer. Admittedly, this definition lacks the power that is needed for eliciting the much-desired Aha! Now I Understand! Moment. Nonetheless it serves as a great starting point for discussing heat and temperature.  How a Thermometer Works Today, there are a variety of types of thermometers. The type that most of us are familiar with from science class is the type that consists of a liquid encased in a narrow glass column. Older thermometers of this type used liquid mercury. Liquid thermometers are based on the principal of thermal expansion. When a substance gets hotter, it expands to a greater volume. Nearly all substances exhibit this behavior of thermal expansion. It is the basis of the design and operation of thermometers. As the temperature of the liquid in a thermometer increases, its volume increases. The liquid is enclosed in a tall, narrow glass (or plastic) column with a constant cross-sectional area. The increase in volume is thus due to a change in height of the liquid within the column. The increase in volume, and thus in the height of the liquid column, is proportional to the increase in temperature. Suppose that

Lesson 10

a 10-degree increase in temperature causes a 1-cm increase in the column’s height. Then a 20-degree increase in temperature will cause a 2-cm increase in the column’s height. And a 30-degree increase in temperature will cause a 3-cm increase in the column’s height. The relationship between the temperature and the column’s height is linear over the small temperature range for which the thermometer is used. This linear relationship makes the calibration of a thermometer a relatively easy task. The calibration of any measuring tool involves the placement of divisions or marks upon the tool to measure a quantity accurately in comparison to known standards. Any measuring tool – even a meter stick – must be calibrated. The tool needs divisions or markings; for instance, a meter stick typically has markings every 1-cm apart or every 1-mm apart. These markings must be accurately placed and the accuracy of their placement can only be judged when comparing it to another object that is precisely known to have a certain length.

A thermometer is calibrated by using two objects of known temperatures. The typical process involves using the freezing point and the boiling point of pure water. Water is known to freeze at 0°C and to boil at 100°C at an atmospheric pressure of 1 atm. By placing a thermometer in a mixture of ice water and allowing the thermometer liquid to reach a stable height, the 0-degree mark can be placed upon the thermometer. Similarly, by placing the thermometer in boiling water (at 1 atm of pressure) and allowing the liquid level to reach a stable height, the 100-degree mark can be placed upon the thermometer. With these two markings placed upon the thermometer, 100 equally

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spaced divisions can be placed between them to represent the 1-degree marks. Since there is a linear relationship between the temperature and the height of the liquid, the divisions between 0 degree and 100 degree can be equally spaced. With a calibrated thermometer, accurate measurements of the temperature of any object can be made within the temperature range for which it has been calibrated. Task №1 Answer the following questions 1. What is temperature? 2. What scale does temperature determine? 3. What does thermometer consist of? 4. When does water freeze? 5. Is a thermometer calibrated by using two objects of known temperatures? Task №2 text

Match the following words with the correct definition according to the 1) Temperature 2) Fahrenheit 3) Thermometer 4) Volume 5) Calibration

is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains. is a device that measures temperature or a temperature gradient using a variety of different principles A measure of the warmth or coldness of an object or substance with reference to some standard value. is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device is a temperature  scale based on one proposed in 1724 by the German physicist 1–c 2–e 3–b 4–a 5–d

Lesson 10 Task №3 Find the equivalents to the following words in the text and make up sentences with them: Increase, placement, relationship, object, column, mixture, type. Task №4 Give explanations for the following words: Liquid, substance, height, space, measurement, object, involve, due. Task №5 1.Where is ___ nearest gas station? a an the d) – 2. I want to introduce you to Sharon. She is ___ very nice person. a an the d) – 3. I want to buy ___ special orchid for my daughter on her birthday. I haven’t picked one out yet, but I’m sure I’ll find the right one soon. a an the d) – 4. Quick! Someone call ___ police. I need help right now. a an the d) – 5. I like your ___ shirt. It’s so pretty. a an the d) – 6. I like ___ beautiful, brown coffee table in your living room. Where did you buy it? a an the – 7. What does he do for ___ living? a

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Introduction to the World of Physics an the d) – 8. We’re studying ___ Italian Renaissance period in art history at the moment. a an the d) – 9. It’s really hot here. We live close to ___ equator. a an the d) – 10. I want to see ___ Pacific Ocean in the summer. Let’s go to San Francisco. a an the – Task № 6 Put the verbs in brackets in the Past Simple or in the Present Perfect. 1. I ________ (never/ be) to the USA. I ______ (want) to go there last summer but I couldn’t. 2. He _______ (live) in this street all his life. 3. His father ________ (come back) to London last Sunday. 4. Yan __________ (write) a letter to Nick two days ago. 5. He ________ (send) his letter yesterday. 6. They ________ (just/ buy)

Lesson 11

LESSON 11 Active vocabulary Scale – шка­ла Relationship – от­но­ше­ния Distribution – расп­ре­де­ле­ние Particulate – час­тиц average kinetic energy – сред­няя ки­не­ти­чес­кая энер­гия particle – час­ти­цы Increasing – Уве­ли­че­ние Collisions – столк­но­ве­ния

Rotation – вра­ще­ние Consider – расс­мат­ри­вать Description – опи­са­ние Location – рас­по­ло­же­ние Measurements – из­ме­ре­ния Compose – со­чи­нять, сос­тав­лять Predominant – преоб­ла­даю­щий Represented – предс­тав­лен­ный

Text 11 Temperature Scales The thermometer calibration process described above results in what is known as a centigrade thermometer. A centigrade thermometer has 100 divisions or intervals between the normal freezing point and the normal boiling point of water. Today, the centigrade scale is known as the Celsius scale, named after the Swedish astronomer Anders Celsius who is credited with its development. The Celsius scale is the most widely accepted temperature scale used throughout the world. It is the standard unit of temperature measurement in nearly all countries, the most notable exception being the United States. Using this scale, a temperature of 28 degrees Celsius is abbreviated as 28°C. Traditionally slow to adopt the metric system and other accepted units of measurements, the United States more commonly uses the Fahrenheit temperature scale. A thermometer can be calibrated using the Fahrenheit scale in a similar manner as was described above. The difference is that the normal freezing point of water is designated as 32 degrees and the normal boiling point of water is designated as 212 degrees in the Fahrenheit scale. There are 180 divisions or intervals between these two temperatures when using the Fahrenheit scale. The Fahrenheit scale is named in honor of German physicist Daniel Fahrenheit. A temperature of 76 degree Fahrenheit is abbreviated as 76°F. In most countries throughout the world, the Fahrenheit scale has been replaced by the use of the Celsius scale.

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Temperatures expressed by the Fahrenheit scale can be converted to the Celsius scale equivalent using the equation below: °C = (°F - 32°)/1.8 Similarly, temperatures expressed by the Celsius scale can be converted to the Fahrenheit scale equivalent using the equation below: °F= 1.8•°C + 32° The Kelvin Temperature Scale While the Celsius and Fahrenheit scales are the most widely used temperature scales, there are several other scales that have been used throughout history. For example, there is the Rankine scale, the Newton scale and the Romer scale, all of which are rarely used. Finally, there is the Kelvin temperature scale, which is the standard metric system of temperature measurement and perhaps the most widely used temperature scale among scientists. The Kelvin temperature scale is similar to the Celsius temperature scale in the sense that there are 100 equal degree increments between the normal freezing point and the normal boiling point of water. However, the zero-degree mark on the Kelvin temperature scale is 273.15 units cooler than it is on the Celsius scale. So a temperature of 0 Kelvin is equivalent to a temperature of -273.15 °C. Note that the degree symbol is not used with this system. So a temperature of 300 units above 0 Kelvin is referred to as 300 Kelvin and not 300 degree Kelvin; such a temperature is abbreviated as 300 K. Conversions between Celsius temperatures and Kelvin temperatures (and vice versa) can be performed using one of the two equations below. °C = K - 273.15° K = °C + 273.15 The zero point on the Kelvin scale is known as absolute zero. It is the lowest temperature that can be achieved. The concept of an absolute temperature minimum was promoted by Scottish physicist William Thomson (Lord Kelvin) in 1848. Thomson theorized based on thermodynamic principles that the lowest temperature which

Lesson 11

could be achieved was -273°C. Prior to Thomson, experimentalists such as Robert Boyle (late 17th century) were well aware of the observation that the volume (and even the pressure) of a sample of gas was dependent upon its temperature. Measurements of variations of pressure and volume with changes in the temperature could be made and plotted. Plots of volume vs. temperature (at constant pressure) and pressure vs. temperature (at constant volume) reflected the same conclusion – the volume and the pressure of a gas reduces to zero at a temperature of -273°C. Since these are the lowest values of volume and pressure that are possible, it is reasonable to conclude that -273°C is the lowest temperature that is possible.

Thomson referred to this minimum lowest temperature as absolute zero and argued that a temperature scale be adopted that had absolute zero as the lowest value on the scale. Today, that temperature scale bears his name. Scientists and engineers have been able to cool matter down to temperatures close to -273.15°C, but never below it. In the process of cooling matter to temperatures close to absolute zero, a variety of unusual properties has been observed. These properties include superconductivity, superfluidity and a state of matter known as a Bose-Einstein condensate. Temperature as a Measure of Kinetic Energy It is at this point that we can use a more sophisticated definition of temperature. Temperature is a measure of the average kinetic energy of particles within a sample of matter. An object or a particle

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that is moving has kinetic energy. There are three common forms of kinetic energy – vibrational kinetic energy, rotational kinetic energy and translational kinetic energy. Up to this point, we have associated kinetic energy with the movement of an object (or particle) from one location to another. This is referred to as translational kinetic energy. A ball moving through space has translational kinetic energy. But an object can also have vibrational kinetic energy; this is the energy of motion possessed by an object that is oscillating or vibrating about a fixed position. And a mass attached to a spring has vibrational kinetic energy. Such a mass is not permanently displaced from its position like a ball moving through space. Finally, an object can have rotational kinetic energy; this is the energy associated with an object that is rotating about an imaginary axis of rotation. A spinning top isn’t moving through space and isn’t vibrating about a fixed position, but there is still kinetic energy associated with its motion about an axis of rotation. This form of kinetic energy is called rotational kinetic energy. A sample of matter consists of particles that can be vibrating, rotating and moving through the space of its container. So at the particle level, a sample of matter possesses kinetic energy. A warm cup of water on a countertop may appear to be as still as can be; yet the particles that are contained within it have kinetic energy. At the particle level, there are atoms and molecules that are vibrating, rotating and moving through the space of its container. Stick a thermometer in the cup of water and you will see the evidence that the water possesses kinetic energy. The water’s temperature, as reflected by the thermometer’s reading, is a measure of the average amount of kinetic energy possessed by the water molecules. When the temperature of an object increases, the particles that compose the object begin to move faster. They either vibrate more rapidly, rotate with greater frequency or move through space with a greater speed. Increasing the temperature causes an increase in the particle speed. So as a sample of water in a pot is heated, its molecules begin to move with greater speed and this greater speed is reflected by a higher thermometer reading. Similarly, if a sample of water is placed in the freezer, its molecules begin to move slower (with a lower speed) and this is reflected by a lower thermometer reading. Boltzmann Speed Distribution and Average Kinetic Energy At the onset of this page, temperature was defined as a measure of the average amount of kinetic energy possessed by an object. But

Lesson 11

what exactly is meant by average kinetic energy? In any sample of matter, particles are moving. Consider the sample of helium gas inside of a helium-filled balloon. The predominant motion of the helium atoms is translational motion. The helium atoms move through the space of the balloon from one location to another. As they do, they encounter collisions with one another and with the balloon walls. These collisions result in changes in speed and direction. As a result, there is not a single speed at which the helium atoms move, but a range of speeds. As there is a range of speeds with which the helium atoms move, there is a range of kinetic energies possessed by these particles. This is often referred to as a Boltzmann speed distribution and is represented graphically by the diagram below. Boltzmann speed distribution

The temperature is more than what the thermometer reads; it is a reflection of the average kinetic energy with which the particles move. The macroscopic description of matter – a thermometer reading – is tied to a particulate description of matter – the speed at which particles move. Now we have to probe the question: what is the relationship between temperature and heat? What is heat? Is temperature the same thing as heat? Is temperature in any way related to heat? What is the cause of heat?

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Exercise №1 Complete each sentence with one of the words from the box. Use each word once only. Celsius scale abbreviated Fahrenheit temperature Kelvin temperature absolute zero absolute temperature minimum -273°C 1)Today, the centigrade scale is known as the________, named after the Swedish astronomer Anders Celsius who is credited with its development. 2) Using this scale, a temperature of 28 degrees Celsius is ________as 28°C. 3) Traditionally slow to adopt the metric system and other accepted units of measurements, the United States more commonly uses the _________scale. 4) Finally, there is the__________, which is the standard metric system of temperature measurement and perhaps the most widely used temperature scale among scientists. 5) The zero point on the Kelvin scale is known as_________. 6) The concept of an absolute temperature minimum was promoted by Scottish physicist William Thomson ( Lord Kelvin) in 1848. 7) Since these are the lowest values of volume and pressure that are possible, it is reasonable to conclude that_________is the lowest temperature that is possible. Exercise №2 Use a word or from A and a word from B to complete the sentences: A 1) There are three common forms of kinetic energy – 2) When the temperature of an object increases, 3) Finally, an object can have rotational kinetic energy; this is the energy associated with an object 4) The Kelvin temperature scale is similar to the Celsius temperature scale in the sense that there are 5) Prior to Thomson, experimentalists such as Robert Boyle (late 17th century) were well aware of the observation that the volume (and even the pressure) of a sample of gas was dependent B 100 equal degree increments between the normal freezing point and the normal boiling point of water. vibrational kinetic energy, rotational kinetic energy and translational kinetic energy. the particles that compose the object begin to move faster. upon its temperature. that is rotating about an imaginary axis of rotation.

Lesson 11 Exercise № 3 Which tenses are used in these sentences: a) In most countries throughout the world, the Fahrenheit scale has been replaced by the use of the Celsius scale. b) The concept of an absolute temperature minimum was promoted by Scottish physicist William Thomson ( Lord Kelvin) in 1848. c) Thomson referred to this minimum lowest temperature as absolute zero and argued that a temperature scale be adopted that had absolute zero as the lowest value on the scale. d) Thomson theorized based on thermodynamic principles that the lowest temperature which could be achieved was -273°C. e) The zero point on the Kelvin scale is known as absolute zero. Exercise №4 Complete the sentences: 1) Temperatures expressed by the________ scale can be converted to the Celsius scale equivalent using the equation below °C = (°F - 32°)/1.8 2) Similarly, temperatures expressed by the _______scale can be converted to the Fahrenheit scale equivalent using the equation below: °F= 1.8•°C + 32° 3) ________referred to this minimum lowest temperature as absolute zero and argued that a temperature scale be adopted that had absolute zero as the lowest value on the scale. 4) ________is a measure of the average kinetic energy of particles within a sample of matter. 5) Similarly, if a sample of water is placed in the freezer, its molecules begin to move _______ (with a lower speed) and this is reflected by a lower thermometer reading Exercise № 5 Do you agree with that? Yes No 1) The thermometer calibration process described above results in what is known as a centigrade thermometer. ______ 2) In most countries throughout the world, the Fahrenheit scale has been replaced by the use of the Celsius scale. ______ 3) Traditionally slow to adopt the metric system and other accepted units of measurements, the United States more commonly uses the Celsius temperature scale. _______ 4) Scientists and engineers have been able to cool matter down to temperatures close to -273.15°C,and below it. 5) The difference is that the normal freezing point of water is designated as 50 degrees and the normal boiling point of water is designated as 212 degrees in the Fahrenheit scale

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LESSON 12 Active vocabulary pondered – об­ду­мы­ваемый accepted notion – при­ня­тое по­ня­тие fluid – жид­кость combustible material – го­рю­чий ма­те­ри­ал surroundings – сре­да observed – наб­лю­даемый explained – объяс­нен­ный substance – ве­ще­ст­во

stuff – ма­те­ри­ал conserved – сох­ра­нен­ный gained – по­лу­чен­ный transferred – пе­ре­дан­ный latent – ск­ры­тый sensible – ра­зум­ный thermal equilibrium – теп­ло­вое рав­но­ве­сие

Text 12 The Caloric Theory Scientists have long pondered the nature of heat. In the mid-19th century, the most accepted notion of heat was one that associated it with a fluid known as caloric. Noted chemist Antoine Lavoisier reasoned that there were two forms of caloric – the kind that was latent or stored in combustible materials and the kind that was sensible and observable through a temperature change. For Lavoisier and his followers, the burning of fuel resulted in the release of this latent heat to the surroundings where it was observed to cause a temperature change of the surroundings. If a hot kettle of water cooled down to room temperature, it was explained by the flow of caloric from the hot water to the surroundings. According to caloric theory, heat was material in nature. It was a physical substance. It was stuff. Like all stuff in Lavoisier’s world, caloric was a conserved substance. Similar to our modern view of heat, the colorist view was that if caloric was released by one object, then it was gained by another object. The total amount of caloric never changed; it was simply transferred from one object to another

Lesson 12

and transformed from one type (latent) to another type (sensible). But unlike our modern view of heat, caloric was an actual physical substance – a fluid that could flow from one object to another. And unlike our modern view, heat was always present in one form or another. Finally, in the modern view, heat is present only when there is an energy transfer. It is senseless to speak of the heat as still existing once the two objects have come to thermal equilibrium. Heat is not something contained in an object; rather it is something transferred between objects. The heat no longer exists when the transfer ceases. Task № 1 Answer the questions 1. When the most accepted notion of heat was one that associated it with a fluid known as caloric? 2. Who reasoned that there were two forms of caloric? 3. What was material in nature according to caloric theory? 4. When is heat present? 5. Heat is not something contained in an object, is it? Task № 2 Put in a/an or the where necessary. Finally, in ____ modern view, heat is present only when there is ___ energy transfer. It is senseless to speak of ___ heat as still existing once ____two objects have come to thermal equilibrium. Heat is not something contained in ___ object; rather it is something transferred between objects. ____heat no longer exists when ____ transfer ceases. Task № 3 Make questions for these sentences. 1. Scientists have long pondered the nature of heat. 2. Noted chemist Antoine Lavoisier reasoned that there were two forms of caloric – the kind that was latent or stored in combustible materials and the kind that was sensible and observable through a temperature change. 3. According to caloric theory, heat was material in nature. 4. The total amount of caloric never changed. 5. In the modern view, heat is present only when there is an energy transfer.

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Introduction to the World of Physics Task № 4 Put in a preposition. According ___ caloric theory, heat was material ____ nature. ____ was ____ physical substance. ____ was stuff. Like all stuff ____ Lavoisier’s world, caloric was ____ conserved substance. Similar ____ our modern view ___ heat, the colorist view was that if caloric was released by one object, then it was gained by another object. Task № 5 Put the verb into the correct form. Noted chemist Antoine Lavoisier 1. _____(reason) that there were two forms of caloric – the kind that was latent or 2.______(stor) in combustible materials and the kind that was sensible and observable through a temperature change. For Lavoisier and his followers, the 3.____(burn) of fuel 4._____ (result) in the release of this latent heat to the surroundings where it was 5.____(observe) to cause a temperature change of the surroundings. Task № 6 Translate underlined words According to caloric theory, heat was material in nature. It was a physical substance. It was stuff. Noted chemist Antoine Lavoisier reasoned that there were two forms of caloric – the kind that was latent or stored in combustible materials and the kind that was sensible and observable through a temperature change.

LESSON 13 Active vocabulary challenges – проб­ле­мы caloric theory – теп­ло­вая теория barrels – бар­ре­ли cannons – ору­дия shavings – ст­руж­ка advocated – за­щи­щен­ный suggesting – пред­ло­же­ние fateful blow – ро­ко­вой удар paddle wheel – греб­ное ко­ле­со measure – ме­ра current – ток

conserve – сох­ра­нить surroundings – сре­да stored – сох­ра­нен­ный bonds – свя­зи created – соз­дан­ный review – об­зор ability – спо­соб­ность transfer – пе­ре­да­ча surroundings – сре­да equilibrium – рав­но­ве­сие

Lesson 13

Text 13 The Fall of Caloric Theory While there were always alternatives to the caloric theory, it was the most accepted view up until the mid-19th century. One of the first challenges to the caloric theory was from Anglo-American scientist Benjamin Thompson (Count Rumford). Thompson was one of the primary scientists appointed to the task of boring out the barrels of cannons for the British government. Thompson was amazed by high temperatures reached by the cannons and by the shavings that were shed from the cannons during the boring process. In one experiment, he immersed the cannon in a tank of water during the boring process and observed that the heat generated by the boring process was capable of boiling the surrounding water within a few hours. Thompson demonstrated that this heat generation occurred in the absence of any chemical or physical change in the cannon’s composition. He attributed the generation of heat to friction between the cannon and the boring tool and argued that it could not have been the result of the flow of fluid into the water. Thompson published a paper in 1798 that challenged the view that heat was a fluid that was conserved. He advocated a mechanical view of heat, suggesting that its origin was related to the motion of atoms and not the transfer of a fluid.

English physicist James Prescott Joule took up where Thompson left off, delivering several fateful blows to the caloric theory through

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a collection of experiments. Joule, for whom the standard metric unit of energy is now named, performed experiments in which he experimentally related the amount of mechanical work to the amount of heat transferred from the mechanical system. In one experiment, Joule allowed falling weights to turn a paddle wheel that was submerged in a reservoir of water. A drawing of the apparatus is depicted at the picture. The falling weights did work on the paddle wheel, which in turn heated the water. Joule measured both the amount of mechanical work done and the amount of heat gained by the water. Similar experiments demonstrating that heat could be generated by an electric current dealt a further blow to the thought that heat was a fluid that was contained within substances and was always conserved. As we will learn further, objects possess internal energy. In chemical reactions, a portion of this energy can be released to the surroundings in the form of heat. However, this internal energy is not a material substance or a fluid contained by the object. It is simply the potential energy stored in the bonds that hold particles within the object together. Heat or thermal energy is the form this energy possesses when it is being transferred between systems and surroundings. There is nothing material about heat. It is neither a substance nor a fluid that is conserved. Heat is a form of energy that can be transferred from one object to another or even created at the expense of the loss of other forms of energy. To review, temperature is a measure of the ability of a substance, or more generally of any physical system, to transfer heat energy to another physical system. If two objects – or if a system and its surroundings – have a different temperature, then they have a different ability to transfer heat. Over time, there will be a flow of energy from the hotter object to the cooler object. This flow of energy is referred to as heat. The heat flow causes the hotter object to cool down and the colder object to warm up. The flow of heat will continue until they reach the same temperature. At this point, the two objects have established a thermal equilibrium with each other.   Task № 1 Answer the questions 1. Who was one of the primary scientists appointed to the task of boring out the barrels of cannons for the British government? 2. What did Thompson demonstrate?

Lesson 13 3. For what was Thompson amazed by? 4. What did Thompson publish in 1798? 5. Did the falling weights work on the paddle wheel?How? Task № 2 Put in a/an or the where necessary. In one experiment, Joule allowed falling weights to turn ___ paddle wheel that was submerged in ___ reservoir of water. ___ drawing of t___ apparatus is depicted at the picture. ___ falling weights did work on ___ paddle wheel, which in turn heated ___ water. Joule measured both ___ amount of mechanical work done and ___ amount of heat gained by ___ water. Similar experiments demonstrating that heat could be generated by ___ electric current dealt ___ further blow to the thought that heat was ___ fluid that was contained within substances and was always conserved. Task № 3 Make questions for these sentences. 1. While there were always alternatives to the caloric theory, it was the most accepted view up until the mid-19th century. 2. Thompson published a paper in 1798 that challenged the view that heat was a fluid that was conserved. 3. Joule measured both the amount of mechanical work done and the amount of heat gained by the water 4. It is simply the potential energy stored in the bonds that hold particles within the object together. 5. The heat flow causes the hotter object to cool down and the colder object to warm up. Task № 4 Put in a preposition. ___ chemical reactions, a portion ___ this energy can be released ___ the surroundings ___ the form ___ heat. However, this internal energy ___ not ___ material substance or ___ fluid contained by the object. It ___ simply the potential energy stored ___ the bonds that hold particles within ___ object together. Task № 5 Put the verb into the correct form. In one experiment, he 1.______(immerse) the cannon in a tank of water during the boring process and 2.____(observe) that the heat 3._____(generate) by the boring process was capable of 3._____(boil) the 4.________(surround) water within a few hours. Thompson 5.________(demonstrate) that this heat

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Introduction to the World of Physics generation occurred in the absence of any chemical or physical change in the cannon’s composition. Task № 6 Translate underlined words As we will learn further, objects possess internal energy. In chemical reactions, a portion of this energy can be released to the surroundings in the form of heat. However, this internal energy is not a material substance or a fluid contained by the object. It is simply the potential energy stored in the bonds that hold particles within the object together.

LESSON 14 Active vocabulary Semiconductor – по­луп­ро­вод­ник Tightly – жест­ко energy bands – энер­ге­ти­чес­кие зо­ны quantum – кван­то­вые state – сос­тоя­ния insulators – изо­ля­то­ры distinguished – от­ли­чают­ся excited – выз­вать arbitrary – произ­воль­ный bandgap – зап­ре­щен­ная conduct – про­во­дить current – ток

electrical conductivity – элект­ри­ чес­кая про­во­ди­мос­ть holes – дыр­ки unoccupied – не­за­ня­тые particles – час­ти­цы covalent – ко­ва­ле­нт­ные recombination – ре­ком­би­на­ция Carrier – но­си­тель Concentration – кон­цент­ра­ция Conducting – про­во­дить Thermal – тер­ми­чес­кое Equilibrium – рав­но­ве­сие

Text 14 Physics of semiconductors Band structure Band structure of a semiconductor showing a full valence band and an empty conduction band.

Lesson 14

Like in other solids, the electrons in semiconductors can have energies only within certain bands between the energy of the ground state, corresponding to electrons tightly bound to the atomic nuclei of the material, and the free electron energy, which is the energy required for an electron to escape entirely from the material. The energy bands each correspond to a large number of discrete quantum states of the electrons, and most of the states with low energy are full, up to a particular band called the valence band. Semiconductors and insulators are distinguished from metals because the valence band in the former materials is very nearly full under normal conditions. The ease with which electrons in a semiconductor can be excited from the valence band to the conduction band depends on the band gap between the bands, and it is the size of this energy bandgap that serves as an arbitrary dividing line (roughly 4eV) between semiconductors and insulators. The electrons must move between states to conduct electric current, and due to the Pauli exclusion principle full bands do not contribute to the electrical conductivity. However, as the temperature of a semiconductor rises above absolute zero, the states of the electrons are increasingly randomized, or smeared out, and some electrons are

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likely to be found in states of the conduction band, which is the band immediately above the valence band. The current-carrying electrons in the conduction band are known as «free electrons,» although they are often simply called «electrons» if context allows this usage to be clear. Electrons excited to the conduction band also leave behind electron holes, or unoccupied states in the valence band. Both the conduction band electrons and the valence band holes contribute to electrical conductivity. The holes themselves don’t actually move, but a neighboring electron can move to fill the hole, leaving a hole at the place it has just come from, and in this way the holes appear to move, and the holes behave as if they were actual positively charged particles. This behavior may also be viewed in relation to chemical bonding. The electrons that have enough energy to be in the conduction band have broken free of the covalent bonds between neighboring atoms in the solid, and are free to move around, and hence conduct charge. It is an important distinction between conductors and semiconductors that, in semiconductors, movement of charge (current) is facilitated by both electrons and holes. Contrast this to a conductor where the Fermi level lies within the conduction band, such that the band is only half filled with electrons. In this case, only a small amount of energy is needed for the electrons to find other unoccupied states to move into, and hence for current to flow. Carrier generation and recombination When ionizing radiation strikes a semiconductor, it may excite an electron out of its energy level and consequently leave a hole. This process is known as electron-hole pair generation. Electron-hole pairs are constantly generated from thermal energy as well, in the absence of any external energy source. Electron-hole pairs are also apt to recombine. Conservation of energy demands that these recombination events, in which an electron loses an amount of energy larger than the band gap, be accompanied by the emission of thermal energy (in the form of phonons) or radiation (in the form of photons). Carrier concentration The concentration of dopant introduced to an intrinsic semiconductor determines its concentration and indirectly affects many of its electrical

Lesson 14

properties. The most important factor that doping directly affects is the concentration of material’s carrier. In an intrinsic semiconductor under thermal equilibrium, the concentration of electrons and holes is equivalent. That is, n = p = ni where n is the concentration of conducting electrons, p is the electron hole concentration, and ni is the material’s intrinsic carrier concentration. Intrinsic carrier concentration varies between materials and is dependent on temperature. Silicon’s ni, for example, is roughly 1×1010 cm-3 at 300 kelvins (room temperature). In general, an increase in doping concentration affords an increase in conductivity due to the higher concentration of carriers available for conduction. Degenerately (very highly) doped semiconductors have conductivity levels comparable to metals and are often used in modern integrated circuits as a replacement for metal. Often superscript plus and minus symbols are used to denote relative doping concentration in semiconductors. For example, n + denotes an n-type semiconductor with a high, often degenerate, doping concentration. Similarly, p − would indicate a very lightly doped p-type material. It is useful to note that even degenerate levels of doping imply low concentrations of impurities with respect to the base semiconductor. In crystalline intrinsic silicon, there are approximately 5×1022 atoms/cm³. Doping concentration for silicon semiconductors may range anywhere from 1013 cm-3 to 1018 cm-3. Doping concentration above about 1018 cm-3 is considered degenerate at room temperature. Degenerately doped silicon contains a proportion of impurity to silicon in the order of parts per thousand. This proportion may be reduced to parts per billion in very lightly doped silicon. Typical concentration values fall somewhere in this range and are tailored to produce the desired properties in the device that the semiconductor is intended for. Effect on band structure Band diagram of a p+n junction. The band bending is a result of the positioning of the Fermi levels in the p+ and n sides.

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Doping a semiconductor crystal introduces allowed energy states within the band gap but very close to the energy band that corresponds to the dopant type. In other words, donor impurities create states near the conduction band while acceptors create states near the valence band. The gap between these energy states and the nearest energy band is usually referred to as dopant-site bonding energy or EB and is relatively small. For example, the EB for boron in silicon bulk is 0.045 eV, compared with silicon’s band gap of about 1.12 eV. Because EB is so small, it takes little energy to ionize the dopant atoms and create free carriers in the conduction or valence bands. Usually the thermal energy available at room temperature is sufficient to ionize most of the dopant. Dopants also have the important effect of shifting the material’s Fermi level towards the energy band that corresponds to the dopant with the greatest concentration. Since the Fermi level must remain constant in a system in thermodynamic equilibrium, stacking layers of materials with different properties leads to many useful electrical properties. For example, the p-n junction’s properties are due to the energy band bending that happens as a result of lining up the Fermi levels in contacting regions of p-type and n-type material. This effect is shown in a band diagram. The band diagram typically indicates the variation in the valence band and conduction band edges versus some spatial dimension, often denoted x. The Fermi energy is also usually indicated in the diagram. Sometimes the intrinsic Fermi energy, Ei, which is the Fermi level in the absence of doping, is shown. These diagrams are useful in explaining the operation of many kinds of semiconductor devices. Task №1 Answer the following questions 1) What are the semiconductors? 2) What is the electron-hole process? 3) What does concentration of carriers define? 4) What is the alloying of a semiconductor crystal? Task №2 Put questions to the underlined words This process is known as electron–hole pair generation.

Lesson 14 Conservation of energy demands that these recombination events, in which an electron loses an amount of energy larger than the band gap. These diagrams are useful in explaining the operation of many kinds of semiconductor devices. Electron-hole pairs are constantly generated from thermal energy as well, in the absence of any external energy source. These diagrams are useful in explaining the operation of many kinds of semiconductor devices. Task №3 Are these sentences True or false? 1. The energy bands each correspond to a large number of discrete quantum states of the electrons, and most of the states with low energy are full, up to a particular band called the valeuncia band. 2. The current-carrying electrons in the conduction band are known as “free electrons,” 3. Electrons excited to the conduction band don’t leave behind electron holes, or unoccupied states in the valence band. 4. The gap between these energy states and the nearest energy band is usually referred to as dopant-site bonding energy or EB and is relatively huge. 5. The band diagram typically indicates the variation in the valence band and conduction band edges versus some spatial dimension Task №4 Put definite or indefinite articles, where its necessary Physics is one of __ oldest academic disciplines, perhaps __ oldest through its inclusion of astronomy. Over __ last two millennia, physics was a part of natural philosophy along with chemistry, certain branches of mathematics, and __ biology, but during __ Scientific Revolution in __ 17th century, __ natural sciences emerged as unique research programs in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and __ boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms of other sciences while __ opening new avenues of research in areas such as mathematics and philosophy. Task №5 Put the words in brackets into the correct form Physics (to become) a separate science when early modern Europeans to use) experimental and quantitative methods (to discover) what (to be) now considered to be the laws of physics. Major developments in this period (to include) the replacement of the geocentric model of the solar system with the helio-centric Copernican

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Introduction to the World of Physics model, the laws governing the motion of planetary bodies determined by Johannes Kepler between 1609 and 1619, pioneering work on telescopes and observational astronomy by Galileo Galilei in the 16th and 17th Centuries, and Isaac Newton’s discovery and unification of the laws of motion and universal gravitation that (to come) to bear his name. Newton also (to develop) calculus, the mathematical study of change, which (to provide) new mathematical methods for solving physical problems. Task №6 Translate these sentences. 1. The band diagram typically indicates the variation in the valence band and conduction band edges versus some spatial dimension, often denoted x. 2. Doping a semiconductor crystal introduces allowed energy states within the band gap but very close to the energy band that corresponds to the dopant type. 3. When ionizing radiation strikes a semiconductor, it may excite an electron out of its energy level and consequently leave a hole 4. The holes themselves don’t actually move, but a neighboring electron can move to fill the hole, leaving a hole at the place it has just come from, and in this way the holes appear to move, and the holes behave as if they were actual positively charged particles. 5. The energy bands each correspond to a large number of discrete quantum states of the electrons, and most of the states with low energy are full, up to a particular band called the valence band. Task №7 Choose the right answer. 1. This force causes objects to wear out, creates heat, opposes motion, and can be reduced with the use of lubricants. – gravitational force – frictional force – normal force – tensional force 2. The amount of air resistance depends on the speed of a falling object and – the mass of the object – gravitational pull of the Earth – the time of day the object is falling – amount of surface area of the object 3. An astronaut drops a hammer and an egg while standing on the surface of the moon. Which one will hit the surface first?

Lesson 14 – the egg – the hammer – both will land at the same time – neither, both will float off into space 4. What is the invisible force of attraction between masses? – remote-sensing – free-fall – gravity – ultraviolet radiation – ozone concentration layer – none of the above 5. Stored energy is called – thermal energy – kinetic energy – mechanical energy – potential energy 6. Which of the following is not used to calculate potential energy? – mass – height – gravitational acceleration – speed 7. What is equal to the product of mass and velocity? – inertia – force of gravity – weight – momentum 8. Dylan was sitting in a chair. He decided to lean back in the chair and balance it on its back legs. A few moments later the legs collapsed, because even though his weight had not changed, it was distributed over only two legs instead of all four. For what concept does this example provide the BEST analogy? – Mass – Volume – Temperature – Density – Pressure

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LESSON 15 Active vocabulary heat – теп­ло­та boil – ки­пя­щая(во­да) Nuclear power – ядер­ная си­ла electricity – элект­ри­че­ст­во Renewable energy – вос­станов­ляемая энер­гия nuclear fusion – ядер­ный син­тез

desalinating – оп­рес­не­ние neutron – нейт­рон turbine – тур­би­на hydrogen – во­до­род nuclear reactor – ядер­ный реак­тор subsidу – суб­си­дия experiment – экс­пе­ри­мент

Text 15 Nuclear power Nuclear power is a type of nuclear technology involving the controlled use of nuclear reactions to release energy for work, including propulsion, heat, and the generation of electricity. Nuclear energy is produced by a controlled nuclear chain reaction and creates heat – which is used to boil water, produce steam, and drive a steam turbine. The turbine can be used to produce mechanical work and to generate electricity. The use of nuclear power has also engendered much debate. Critics claim that nuclear power is a potentially dangerous energy source with a limited fuel supply (compared to renewable energy), and they note the problems of storing radioactive waste, the potential for radioactive contamination by accident or sabotage, and the possibility of nuclear proliferation. Advocates claim that these risks are small and can be further reduced by the technology in new reactors, and the safety record is good when compared to other major types of power plants. In addition, they note that many renewable energy technologies have not solved the problem of their intermittent power production. As of 2004, nuclear power provided 6.5 percent of the world’s energy and 15.7 percent of the world’s electricity, with the U.S., France, and Japan together accounting for 57 percent of all nuclear generated electricity. As of 2007, the IAEA reported that there were 435 nuclear power reactors in operation in the world, operating in 31 different countries.[

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These provided about 17 percent of the world’s electricity. The United States produces the most nuclear energy, with nuclear power providing 20 percent of the electricity it consumes, while France produces the highest percentage of its electrical energy from nuclear reactors – 80 percent as of 2006. In the European Union as a whole, nuclear energy provides 30 percent of the electricity. Nuclear energy policy differs between European Union countries, and some, such as Austria and Ireland, have no active nuclear power stations. In comparison, France has a large number of these plants, with 16 currently in use throughout the country. Many military and some civilian (such as some icebreakers) ships use nuclear marine propulsion, a form of nuclear propulsion. International research is ongoing into different safety improvements such as passively safe plants, the use of nuclear fusion, and additional uses of produced heat such as the hydrogen production (in support of a hydrogen economy), for desalinating sea water, and for use in district heating systems. The first successful experiment with nuclear fission was conducted in 1938, in Berlin, by the German physicists Otto Hahn, Lise Meitner, and Fritz Strassmann. The first man-made reactor, Chicago Pile-1, achieved criticality on December 2, 1942, as part of the Manhattan Project. Electricity was generated for the first time by a nuclear reactor on December 20, 1951, at the EBR-I experimental station near Arco, Idaho, which initially produced about 100 kW. The Arco Reactor was also the first to partially m melt down (in 1955). In 1952, a report by the Paley Commission (The President’s Materials Policy Commission) for President Harry Truman made a «relatively pessimistic» assessment of nuclear power, and called for «aggressive research in the whole field of solar energy». A December 1953 speech by President Dwight Eisenhower, «Atoms for Peace», set the U.S. on a course of strong government support for the international use of nuclear power. Early years The Shippingport Atomic Power Station in Shippingport, Pennsylvania was the first commercial reactor in the USA and was opened in 1957. In 1954, Lewis Strauss, then chairman of the United States Atomic Energy Commission (forerunner of the U.S. Nuclear Regulatory

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Commission) famously spoke of electricity in the future being «too cheap to meter». While few doubt he was thinking of atomic energy when he made the statement, he might have been referring to hydrogen fusion, rather than uranium fission. Actually, the consensus of government and business at the time was that nuclear (fission) power might eventually become merely economically competitive with conventional power sources.

On June 27 1954, the world’s first nuclear power plant generating electricity for a power grid started operations in Obninsk, USSR. The reactor produced 5 megawatts (electrical), enough to power 2,000 homes. In 1955 the United Nations «First Geneva Conference», then the world’s largest gathering of scientists and engineers, met to explore the technology. In 1957, EURATOM was launched alongside the European Economic Community (the latter is now the European Union). The same year also saw the launch of the International Atomic Energy Agency (IAEA). The world’s first commercial nuclear power station, Calder Hall in Sellafield, England was opened in 1956, with an initial capacity of 50 MW (later 200 MW). The Shippingport Reactor (Pennsylvania, 1957) was the first commercial nuclear generator to become operational in the United States. One of the first organizations to develop utilitarian nuclear power was the U.S. Navy, for the purpose of propelling submarines and aircraft carriers. It has a good record in nuclear safety, perhaps because of the stringent demands of Admiral Hyman G. Rickover, who was the driving force behind nuclear marine propulsion. The U.S. Navy has operated more nuclear reactors than any other entity, including the

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Soviet Navy, with no publicly known major incidents. The first nuclearpowered submarine, USS Nautilus (SSN-571), was put to sea in 1955. Two U.S. nuclear submarines, USS Scorpion and Thresher, were lost at sea, though for reasons not related to their reactors, and their wrecks are situated such that the risk of nuclear pollution is considered low. The 1973 oil crisis had a significant effect on the construction of nuclear power plants worldwide. The oil embargo led to a global economic recession, energy conservation, and high inflation that both reduced the projected demand for new electric generation capacity in the United States and made financing of such capital intensive projects difficult. This contributed to the cancellation of over 100 reactor orders in the U.S. Even so, the plants already under construction effectively displaced oil for the generation of electricity. In 1973, oil generated 17 percent of the electricity in the United States. Today, oil is a minor source of electric power (except in Hawaii), while nuclear power now generates 20 percent of the country’s electricity. The oil crisis caused other countries, such as France and Japan, which had relied even more heavily on oil for electric generation (39 percent and 73 percent respectively) to invest heavily in nuclear power. Today, nuclear power supplies about 80 percent and 30 percent of the electricity in those countries, respectively.

Washington Public Power Supply System Nuclear Power Plants 3 and 5 were never completed Installed nuclear capacity initially rose relatively quickly, rising from less than 1 gigawatt (GW) in 1960, to 100 GW in the late 1970s,

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and 300 GW in the late 1980s. Since the late 1980s capacity has risen much more slowly, reaching 366 GW in 2005, primarily due to Chinese expansion of nuclear power. Between around 1970 and 1990, more than 50 GW of capacity was under construction (peaking at over 150 GW in the late 70s and early 80s) – in 2005, around 25 GW of new capacity was planned. More than two-thirds of all nuclear plants ordered after January 1970 were eventually canceled. During the 1970s and 1980s rising economic costs (related to vastly extended construction times largely due to regulatory changes and pressure-group litigation) and falling fossil fuel prices made nuclear power plants then under construction less attractive. In the 1980s (U.S.) and 1990s (Europe), flat load growth and electricity liberalization also made the addition of large new baseload capacity unattractive. A general movement against nuclear power arose during the last third of the twentieth century, based on the fear of a possible nuclear accident and on fears of radiation, as well as in opposition to nuclear waste production, transport, and final storage. Perceived risks on the citizens’ health and safety, the 1979 accident at Three Mile Island, and the 1986 Chernobyl disaster played a part in stopping new plant construction in many countries. However, in the U.S. new construction dropped sharply before the Three Mile Island accident, after the 1973 oil crises, and the Brookings Institution suggests that new nuclear units have not been ordered in the U.S. primarily for economic reasons rather than fears of accidents. Unlike the Three Mile Island accident, the much more serious Chernobyl accident did not increase regulations affecting Western reactors, since the Chernobyl reactors were of the problematic RBMK design only used in the Soviet Union, lacking, for example, containment buildings. An international organization to promote safety awareness and professional development on operators in nuclear facilities was created: WANO; World Association of Nuclear Operators. As of March 1, 2007, Watts Bar 1, which came on-line in 1997, was the last U.S. commercial nuclear reactor to go on-line. This is often quoted as evidence of a successful worldwide campaign for nuclear power phase-out. However, political resistance to nuclear power has only ever been successful in parts of Europe, in New Zealand, in the Philippines, and in the United States. Even in the U.S. and throughout Europe, investment in research and in the nuclear fuel cycle has con-

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tinued, and some experts predict that electricity shortages, fossil fuel price increases, global warming from fossil fuel use, new technology such as passively safe plants, and national energy security will renew the demand for nuclear power plants. Many countries remain active in developing nuclear power, including Japan, China, and India, all actively developing both fast and thermal technology, South Korea and the United States, developing thermal technology only, and South Africa and China, developing versions of the Pebble Bed Modular Reactor (PBMR). Finland and France actively pursue nuclear programs; Finland has a new European Pressurized Reactor under construction by Areva. Japan has an active nuclear construction program with new units brought on-line in 2005. In the U.S., three consortia responded in 2004 to the U.S. Department of Energy’s solicitation under the Nuclear Power 2010 Program and were awarded matching funds – the Energy Policy Act of 2005 authorized subsidies for up to six new reactors, and authorized the Department of Energy to build a reactor based on the Generation IV Very-High-Temperature Reactor concept to produce both electricity and hydrogen. As of the early twenty first century, nuclear power is of particular interest to both China and India to serve their rapidly growing economies – both are developing fast breeder reactors. In the energy policy of the United Kingdom, it is recognized that there is a likely future energy supply shortfall, which may have to be filled by either new nuclear plant construction or maintaining existing plants beyond their programmed lifetime. Conventional thermal power plants all have a fuel source to provide heat. Examples are gas, coal, or oil. For a nuclear power plant, this heat is provided by nuclear fission inside the nuclear reactor. When a relatively large fissile atomic nucleus (usually uranium-235 or plutonium-239) is struck by a neutron, it forms two or more smaller nuclei as fission products, releasing energy and neutrons in a process called nuclear fission. The neutrons then trigger further fission. And so on. When this nuclear chain reaction is controlled, the energy released can be used to heat water, produce steam, and drive a turbine that generates electricity. It should be noted that a nuclear explosive involves an uncontrolled chain reaction, and the rate of fission in a reactor is not capable of reaching sufficient levels to trigger a nuclear explosion because commercial reactor grade nuclear fuel is not enriched to a high enough level.

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The chain reaction is controlled through the use of materials that absorb and moderate neutrons. In uranium-fueled reactors, neutrons must be moderated (slowed down) because slow neutrons are more likely to cause fission when colliding with a uranium-235 nucleus. Light water reactors use ordinary water to moderate and cool the reactors. When at operating temperatures if the temperature of the water increases, its density drops, and fewer neutrons passing through it are slowed enough to trigger further reactions. That negative feedback stabilizes the reaction rate. A number of other designs for nuclear power generation, the Generation IV reactors, are the subject of active research and may be used for practical power generation in the future. A number of the advanced nuclear reactor designs could also make critical fission reactors much cleaner, much safer, and/or much less of a risk to the proliferation of nuclear weapons. Controlled nuclear fusion could in principle be used in fusion power plants to produce power without the complexities of handling actinides, but significant scientific and technical obstacles remain. Several fusion reactors have been built, but as yet none has “produced” more thermal energy than electrical energy consumed. Despite research having started in the 1950s, no commercial fusion reactor is expected before 2050. The ITER project is currently leading the effort to commercialize fusion power. Task № 1 Answer the following questions: 1) What’s nuclear power? 2) How is nuclear power produced? 3) Does the USA produce nuclear power? 4) When was the first successful experiment done with nuclear fission? 5) What countries do nuclear power remain active in developing? Task № 2 Make questions to the underlined words. 1) The use of nuclear power has also engendered much debate. As of 2004, nuclear power provided 6.5 percent of the world’s energy and 15.7 percent of the world’s electricity, with the U.S., France, and Japan together accounting for 57 percent of all nuclear generated electricity.

Lesson 16 The 1973 oil crisis had a significant effect on the construction of nuclear power plants worldwide. A general movement against nuclear power arose during the last third of the twentieth century, based on the fear of a possible nuclear accident and on fears of radiation, as well as in opposition to nuclear waste production, transport, and final storage. Task №3 Find the equivalents to the following words in the text and make up sentences with them. Research, unattractive, include, subsidy. Task №4 Give explanations for the following words: electric generation, energy, nuclear fusion, intermittent. Task № 5 Put definite or indefinite articles ___ general movement against nuclear power arose during the last third of ___ twentieth century, based on ___ fear of ___ possible nuclear accident and on fears of radiation, as well as in opposition to nuclear waste production, transport, and final storage.

LESSON 16 Active vocabulary Accompanied – соп­ро­вож­дае­мый lightest elements – лег­кие эле­мен­ты nucleosynthesis – нук­лео­син­те­за high-energy – вы­со­коэнер­ге­ти­чес­кий self-sustaining – са­мо­под­дер­жи­ ваю­щей­ся thermonuclear temperatures – тер­ моя­дер­ные тем­пе­ра­ту­ры electromagnetic repulsion – элект­ро­маг­нит­ное от­тал­ки­ва­ние positively charged – по­ло­жи­тель­но за­ря­жен­ные

military purposes – воен­ные це­ли occur – проис­хо­дить fully surrounded – пол­ностью ок­ ру­жен immediate – не­мед­лен­ная area-to-volume – пло­щадь к объему ratio – соот­но­ше­ние caused – выз­ван­ный common – об­щий interior – ин­терь­ер fermions – фер­мионы average – сред­ний

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Introduction to the World of Physics neighboring nucleons – со­сед­ние нук­ло­ны opposing forces – про­ти­вос­тоящие си­лы approaches – под­хо­ды release – ос­во­бож­де­ние

excess – из­бы­ток completely – пол­ностью undergo – под­вер­гать­ся Converting – преоб­ра­зо­ва­ние Unstable – ­неустой­чи­вый Anomalously – ано­маль­но

Text 16 Fusion power In physics and nuclear chemistry, nuclear fusion is the process by which multiple atomic particles join together to form a heavier nucleus. It is accompanied by the release or absorption of energy. Iron and nickel nuclei have the largest binding energies per nucleon of all nuclei and therefore are the most stable. The fusion of two nuclei lighter than iron or nickel generally releases energy, while the fusion of nuclei heavier than iron or nickel absorbs energy. Fusion reactions power the stars and produce all but the lightest elements in a process called nucleosynthesis. Whereas the fusion of light elements in the stars releases energy, production of the heaviest elements absorbs energy, so it can only take place in the extremely high-energy conditions of supernova explosions. When the fusion reaction is a sustained uncontrolled chain, it can result in a thermonuclear explosion, such as what is generated by a hydrogen bomb. Reactions that are not self-sustaining can still release considerable energy, as well as large numbers of neutrons. Research into controlled fusion, with the aim of producing fusion power for the production of electricity, has been conducted for over 50 years. It has been accompanied by extreme scientific and technological difficulties, and as of yet has not been successful in producing workable designs. As of the present, the only self-sustaining fusion reactions produced by humans have been produced in hydrogen bombs, where the extreme power of a fission bomb is necessary to begin the process. While some plans have been put forth to attempt to use the explosions of hydrogen bombs to generate electricity (e.g. PACER), none of these has ever moved far past the design stage. It takes considerable energy to force nuclei to fuse, even those of the lightest element, hydrogen. This is because all nuclei have a

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positive charge (due to their protons), and as like charges repel, nuclei strongly resist being put too close together. Accelerated to high speeds (that is, heated to thermonuclear temperatures), however, they can overcome this electromagnetic repulsion and get close enough for the strong nuclear force to be active, achieving fusion. The fusion of lighter nuclei, creating a heavier nucleus and a free neutron, will generally release more energy than it took to force them together–an exothermic process that can produce self-sustaining reactions. The energy released in most nuclear reactions is much larger than that in chemical reactions, because the binding energy that holds a nucleus together is far greater than the energy that holds electrons to a nucleus. For example, the ionization energy gained by adding an electron to a hydrogen nucleus is 13.6 electron volts-less than onemillionth of the 17 MeV released in the D-T (deuterium-tritium) reaction. Fusion reactions have an energy density many times greater than nuclear fission-that is, per unit of mass the reactions produce far greater energies, even though individual fission reactions are generally much more energetic than individual fusion reactions-which are themselves millions of times more energetic than chemical reactions. Only the direct conversion of mass into energy, such as with collision of matter and antimatter, is more energetic per unit of mass than nuclear fusion. Building upon the nuclear transmutation experiments of Ernest Rutherford done a few years earlier, fusion of light nuclei (hydrogen isotopes) was first observed by Mark Oliphant in 1932, and the steps of the main cycle of nuclear fusion in stars were subsequently worked out by Hans Bethe throughout the remainder of that decade. Research into fusion for military purposes began in the early 1940s, as part of the Manhattan Project, but was not successful until 1952. Research into controlled fusion for civilian purposes began in the 1950s, and continues to this day. A substantial energy barrier must be overcome before fusion can occur. At large distances two naked nuclei repel one another because of the repulsive electrostatic force between their positively charged protons. If two nuclei can be brought close enough together, however, the electrostatic repulsion can be overcome by the nuclear force which is stronger at close distances. When a nucleon such as a proton or neutron is added to a nucleus, the nuclear force attracts it to other nucleons, but primarily to its

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immediate neighbors due to the short range of the force. The nucleons in the interior of a nucleus have more neighboring nucleons than those on the surface. Since smaller nuclei have a larger surface areato-volume ratio, the binding energy per nucleon due to the strong force generally increases with the size of the nucleus but approaches a limiting value corresponding to that of a fully surrounded nucleon. The electrostatic force, on the other hand, is an inverse-square force, so a proton added to a nucleus will feel an electrostatic repulsion from all the other protons in the nucleus. The electrostatic energy per nucle-on due to the electrostatic force thus increases without limit as nuclei get larger. The electrostatic force caused by positively charged nuclei are very strong over long distances, but at short distances the nuclear force is stronger. As such, the main technical difficulty for fusion is getting the nuclei close enough to fuse (distances not to scale). The net result of these opposing forces is that the binding energy per nucleon generally increases with increasing size, up to the elements iron and nickel, and then decreases for heavier nuclei. Eventually, the binding energy becomes negative and very heavy nuclei are not stable. The four most tightly bound nuclei, in decreasing order of binding energy, are 62Ni, 58Fe, 56Fe, and 60Ni.[1] Even though the nickel isotope]] 62Ni is more stable, the iron isotope 56Fe is an order of magnitude more common. This is due to a greater disintegration rate for 62Ni in the interior of stars driven by photon absorption. A notable exception to this general trend is the helium-4 nucleus, whose binding energy is higher than that of lithium, the next heavier element. The Pauli exclusion principle provides an explanation for this exceptional behavior–it says that because protons and neutrons are fermions, they cannot exist in exactly the same state. Each proton or neutron energy state in a nucleus can accommodate both a spin up particle and a spin down particle. Helium-4 has an anomalously large binding energy because its nucleus consists of two protons and two neutrons; so all four of its nucleons can be in the ground state. Any additional nucleons would have to go into higher energy states. The situation is similar if two nuclei are brought together. As they approach each other, all the protons in one nucleus repel all the protons in the other. Not until the two nuclei actually come in contact can the strong nuclear force take over. Consequently, even when the final energy state is lower, there is a large energy barrier that must first be overcome. It is called the Coulomb barrier.

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The Coulomb barrier is smallest for isotopes of hydrogen–they contain only a single positive charge in the nucleus. A bi-proton is not stable, so neutrons must also be involved, ideally in such a way that a helium nucleus, with its extremely tight binding, is one of the products. Using deuterium-tritium fuel, the resulting energy barrier is about 0.01 MeV. In comparison, the energy needed to remove an electron from hydrogen is 13.6 eV, about 750 times less energy. The (inter-mediate) result of the fusion is an unstable 5He nucleus, which im-mediately ejects a neutron with 14.1 MeV. The recoil energy of the remaining 4He nucleus is 3.5 MeV, so the total energy liberated is 17.6 MeV. This is many times more than what was needed to overcome the energy barrier. If the energy to initiate the reaction comes from accelerating one of the nuclei, the process is called beam-target fusion; if both nuclei are accelerated, it is beam-beam fusion. If the nuclei are part of a plasma near thermal equilibrium, one speaks of thermonuclear fusion. Temperature is a measure of the average kinetic energy of particles, so by heating the nuclei they will gain energy and eventually have enough to overcome this 0.01 MeV. Converting the units between electronvolts and Kelvin shows that the barrier would be overcome at a temperature in excess of 120 million Kelvin – a very high temperature. There are two effects that lower the actual temperature needed. One is the fact that temperature is the average kinetic energy, implying that some nuclei at this temperature would actually have much higher energy than 0.01 MeV, while others would be much lower. It is the nuclei in the high-energy tail of the velocity distribution that account for most of the fusion reactions. The other effect is quantum tunneling. The nuclei do not actually have to have enough energy to overcome the Coulomb barrier completely. If they have nearly enough energy, they can tunnel through the remaining barrier. For this reason fuel at lower temperatures will still undergo fusion events at a lower rate. Exercise №1 Give explanations for the following words: hydrogen, nuclear reaction, nuclear fission, beam-target fusion, thermonuclear fusion, fusion power, hydrogen isotopes, proton.

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100 Introduction to the World of Physics Exercise №2 Which tenses are used in these sentences: It has been accompanied by extreme scientific and technological difficulties, and as of yet has not been successful in producing workable designs. Research into controlled fusion, with the aim of producing fusion power for the production of electricity, has been conducted for over 50 years. Building upon the nuclear transmutation experiments of Ernest Rutherford done a few years earlier, fusion of light nuclei (hydrogen isotopes) was first observed by Mark Oliphant in 1932. As of the present, the only self-sustaining fusion reactions produced by humans have been produced in hydrogen bombs, where the extreme power of a fission bomb is necessary to begin the process. While some plans have been put forth to attempt to use the explosions of hydrogen bombs to generate electricity (e.g. PACER), none of these has ever moved far past the design stage. Exercise № 3 Underline the correct word or phrase in each sentence: It takes considerable energy to force nuclei to fuse, even those of the lightest element, hydrogen/ electrons. Reactions that are not self-sustaining can still release considerable energy, as well as large numbers of neutrons/proton. Fusion reactions power the stars and produce all but the lightest elements in a process called nucleosynthesis/Fusion power. For example, the ionization energy/ self-sustaining reactions gained by adding an electron to a hydrogen nucleus is 13.6 electron volts–less than onemillionth of the 17 MeV released in the D-T (deuterium-tritium) reaction. At large distances two naked nuclei repel one another because of the repulsive electrostatic force between their positively charged protons. Research into fusion for military purposes began in the early 1940s, as part of the Manhattan Project/ transmutation experiments of Ernest Rutherford, but was not successful until 1952. Exercise №4 Complete the sentences: If the energy to initiate the reaction comes from accelerating one of the nuclei, the process is called _______ fusion . If both nuclei are accelerated, it is _______ fusion. When a nucleon such as a _______or _______is added to a nucleus, the nuclear force attracts it to other nucleons, but primarily to its immediate neighbors due to the short range of the force. The ________barrier is smallest for isotopes of hydrogen–they contain only a single positive charge in the nucleus

Lesson 16 A notable exception to this general trend is the _______-4 nucleus, whose binding energy is higher than that of_______, the next heavier element The_______exclusion principle provides an explanation for this exceptional behavior–it says that because protons and neutrons are fermions, they cannot exist in exactly the same state. Exercise№5 Underline the stressed syllable in these words: nuclear, electrons, reaction, hydrogen, neutrons, additional, consequently, accelerating, exceptional, provides. Exercise №6 Mark the sentences T(true) or False(F): Each proton or neutron energy state in a nucleus can accommodate both a spin up particle and a spin down particle. ___ When a nucleon such as a electron is added to a nucleus, the nuclear force attracts it to other nucleons, but primarily to its immediate neighbors due to the short range of the force. ____ Only the direct conversion of mass into energy, such as with collision of matter and antimatter, is more energetic per unit of mass than nuclear fusion. _____ Building upon the nuclear transmutation experiments of Ernest Rutherford done a few years earlier, fusion of light nuclei (hydrogen isotopes) was first observed by Hans Bethe in 1932. _____ Consequently, even when the final energy state is lower, there is a large energy barrier that must first be overcome. It is called the Coulomb barrier. _____ Research into controlled fusion, with the aim of producing fusion power for the production of electricity, has been conducted for over 10 years. _____ Iron and nickel nuclei have the largest binding energies per nucleon of all nuclei and therefore are the most stable. _____

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102 Introduction to the World of Physics LESSON 17 Active vocabulary Absorb – пог­ло­щать Convection – кон­век­ция Reaches – дос­ти­гает Water vapor – во­дя­ной пар Amplifies – уси­ли­вает Average – сред­ний Convert – кон­вер­ти­ро­вать Reflecting – от­ра­жаю­щий Square – квад­рат Internally – внут­рен­не Engine – дви­га­тель Mirrors – зер­ка­ла Increasing – уве­ли­че­ние Full-scale – в на­ту­раль­ную ве­ли­чи­ну

Station – стан­ция Parabolic troughs – па­ра­бо­ли­чес­ кие же­ло­ба. Cheap oil – де­ше­вая неф­ть Resurrected – воск­рес­ший coal – уголь Industrial Revolution – про­мыш­ лен­ная ре­во­лю­ция fossil fuels – ис­ко­паемое топ­ли­во. oil embargo – неф­тя­ное эм­бар­го energy crisis – энер­ге­ти­чес­кий кри­зис policies – по­ли­сы solar water heating – сол­неч­ный наг­рев во­ды

Text 17 Energy from the Sun

About half the incoming solar energy reaches the Earth’s surface. The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land

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masses. The spectrum of solar light at the Earth’s surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet. Earth’s land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth’s surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C. By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived. In 1897, Frank Shuman, a U.S. inventor, engineer and solar energy pioneer built a small demonstration solar engine that worked by reflecting solar energy onto square boxes filled with ether, which has a lower boiling point than water, and were fitted internally with black pipes which in turn powered a steam engine. In 1908 Shuman formed the Sun Power Company with the intent of building larger solar power plants. He, along with his technical advisor A.S.E. Ackermann and British physicist Sir Charles Vernon Boys, developed an improved the system using mirrors to reflect solar energy upon collector boxes, increasing heating capacity to the extent that water could be used instead of ether. Shuman then constructed a full-scale steam engine powered by low-pressure water, enabling him to patent the entire solar engine system by 1912. Shuman built the world’s first solar thermal power station in Maadi, Egypt between 1912 and 1913. Shuman’s plant used parabolic troughs to power a 45-52 kilowatt (60-70 H.P.) engine that pumped more than 22,000 litters of water per minute from the Nile River to adjacent cotton fields. Although the outbreak of World War I and the discovery of cheap oil in the 1930s discouraged the advancement of solar energy, Shuman’s vision and basic design were resurrected in the 1970s with a new wave of interest in solar thermal energy. In 1916 Shuman was quoted in the media advocating solar energy’s utilization, saying: We have proved the commercial profit of sun power in the tropics and have more particularly proved that after our stores of oil and coal are exhausted the human race can receive unlimited power from the rays of the sun.

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104 Introduction to the World of Physics Beginning with the surge in coal use which accompanied the Industrial Revolution, energy consumption has steadily transitioned from wood and biomass to fossil fuels. The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce. However development of solar technologies stagnated in the early 20th century in the face of the increasing availability, economy, and utility of coal and petroleum. The 1973 oil embargo and 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies. Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the US (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer Institute for Solar Energy Systems ISE). Commercial solar water heaters began appearing in the United States in the 1890s. These systems saw increasing use until the 1920s but were gradually replaced by cheaper and more reliable heating fuels. As with photovoltaics, solar water heating attracted renewed attention as a result of the oil crises in the 1970s but interest subsided in the 1980s due to falling petroleum prices. Development in the solar water heating sector progressed steadily throughout the 1990s and growth rates have averaged 20% per year since 1999. Although generally underestimated, solar water heating and cooling is by far the most widely deployed solar technology with an estimated capacity of 154 GW as of 2007. The International Energy Agency has said that solar energy can make considerable contributions to solving some of the most urgent problems the world now faces: The development of affordable, inexhaustible and clean solar energy technologies will have huge longerterm benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered lear-ning investments; they must be wisely spent and need to be widely shared. In 2011, the International Energy Agency said that solar energy technologies such as photovoltaic panels, solar water heaters and po-

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wer stations built with mirrors could provide a third of the world’s energy by 2060 if politicians commit to limiting climate change. The energy from the sun could play a key role in de-carbonizing the global economy alongside improvements in energy efficiency and imposing costs on greenhouse gas emitters. «The strength of solar is the incredible variety and flexibility of applications, from small scale to big scale». Task № 1 Answer the following questions 1) What energy is from the sun? 2) What is the convection? 3) How does petovatt get land of incoming solar radiation? 4) Why has coal become the most desired item? 5) Was it caused by the reorganization of energy policies around the world? Task № 2 Make questions to the underlined words The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere. However development of solar technologies stagnated in the early 20th  century in the face of the increasing availability, economy, and utility of coal and petroleum. The International Energy Agency has said that solar energy can make considerable contributions to solving some of the most urgent problems the world now faces In 1897, Frank Shuman, a U.S. inventor, engineer and solar energy pioneer built a small demonstration solar engine that worked by reflecting solar energy onto square boxes filled with ether, which has a lower boiling point than water, and were fitted internally with black pipes which in turn powered a steam engine Beginning with the surge in coal use which accompanied the Industrial Revolution, energy consumption has steadily transitioned from wood and biomass to fossil fuels. Task №3 Give explanations for the following words: radiation (insolation); The spectrum of solar light; near-ultraviolet; atmospheric circulation or convection; Parabolic troughs.

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106 Introduction to the World of Physics Task № 4 Put in the missing preposition. 1)___International Energy Agency has said ___ solar energy can make considerable contributions __ solving some ___ most urgent problems __ world now faces:___ development _affordable, inexhaustible___ clean solar energy technologies will have huge longer-term benefits. __ will increase countries’ energy security through reliance ____ indigenous, inexhaustible__ mostly import-independent resource, enhance sustainability, reduce pollution, lower __ costs of mitigating climate change,__ keep fossil fuel prices lower ___ otherwise. Task № 5 Complete the sentences with the relative clause: which, when. 1)___ the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, ___rain onto the Earth’s surface, completing the water cycle. 2) By photosynthesis green plants convert solar energy into chemical energy, ___ produces food, wood and the biomass from___ fossil fuels are derived. 3) In 1897, Frank Shuman, a U.S. inventor, engineer and solar energy pioneer built a small demonstration solar engine that worked by reflecting solar energy onto square boxes filled with ether, ___has a lower boiling point than water, and were fitted internally with black pipes which in turn powered a steam engine Task № 6 Write a summary of the text

LESSON 18 Active vocabulary Motion – дви­же­ние Experiences – ис­пы­ты­вать Observed – наб­лю­дать Behavior – по­ве­де­ние Accelerate – ус­ко­ре­ние Provides – обес­пе­чи­вать unbalanced force – н ­ еу­рав­но­ве­шен­ная си­ла

spinning wheels – прял­ки remains – ос­та­вать­ся subsequently – впос­ледст­вии spills – про­ли­вать direction – нап­рав­ле­ние locked wheels – за­пер­тые ко­ле­са governed – уп­рав­ляет­ся applications – при­ло­же­ния

Lesson 18

Text 18 Everyday Applications of Newton’s First Law There are many applications of Newton’s first law of motion. Consider some of your experiences in an automobile. Have you ever observed the behavior of coffee in a coffee cup filled to the rim while starting a car from rest or while bringing a car to rest from a state of motion? Coffee “keeps on doing what it is doing.” When you accelerate a car from rest, the road provides an unbalanced force on the spinning wheels to push the car forward; yet the coffee (that was at rest) wants to stay at rest. While the car accelerates forward, the coffee remains in the same position; subsequently, the car accelerates out from under the coffee and the coffee spills in your lap. On the other hand, when braking from a state of motion the coffee continues forward with the same speed and in the same direction, ultimately hitting the windshield or the dash. Coffee in motion stays in motion. Have you ever experienced inertia (resisting changes in your state of motion) in an automobile while it is braking to a stop? The force of the road on the locked wheels provides the unbalanced force to change the car’s state of motion, yet there is no unbalanced force to change your own state of motion. Thus, you continue motion sliding along the seat in forward motion. A person in motion stays in motion with the same speed and in the same direction ... unless acted upon by the unbalanced force of a seat belt. Yes! Seat belts are used to provide safety for passengers whose motion is governed by Newton’s laws. The seat belt provides the unbalanced force that brings you from a state of motion to a state of rest.  There are many more applications of Newton’s first law of motion. Several applications are listed below. Perhaps you could think about the law of inertia and provide explanations for each application. – Blood rushes from your head to your feet while quickly stopping when riding on a descending elevator.

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108 Introduction to the World of Physics – The head of a hammer can be tightened onto the wooden handle by banging the bottom of the handle against a hard surface. – A brick is painlessly broken over the hand of a physics teacher by slamming it with a hammer. (CAUTION: do not attempt this at home!) – To dislodge ketchup from the bottom of a ketchup bottle, it is often turned upside down and thrusted downward at high speeds and then abruptly halted. – Headrests are placed in cars to prevent whiplash injuries during rear-end collisions. – While riding a skateboard (or wagon or bicycle), you fly forward off the board when hitting a curb or rock or other object that abruptly halts the motion of the skateboard. Task № 1 Answer the following questions 1) What is the acceleration? 2) What is the unbalanced force? 3) What is first law of Newton about? 4) What is the inertia? 5) Can you give examples on the first law of Newton? Task № 2 Put questions to the underlined words 1) There are many applications of Newton’s first law of motion 2) Consider some of your experiences in an automobile. 3) On the other hand, when braking from a state of motion the coffee continues forward with the same speed and in the same direction, ultimately hitting the windshield or the dash. A person in motion stays in motion with the same speed and in the same direction ... unless acted upon by the unbalanced force of a seat belt. Perhaps you could think about the law of inertia and provide explanations for each application Task №3 Find the equivalents to the following words in the text and make up sentences with them Motion, experiences, unbalanced force, coffee, accelerate.

Lesson 19 Task № 4 Put definite or indefinite articles 1) There __ many applications _ Newton’s first law _ motion. 2) Consider some _ your experiences _ _ automobile. 3) Have you ever experienced inertia _ _ automobile while _ _ braking to _ stop? 4) The seat belt provides the unbalanced force that brings you from _state _ motion to _ state _ rest. 5) To dislodge ketchup from the bottom _ _ketchup bottle, _ _ often turned upside down and thrusted downward at high speeds and then abruptly halted. Task № 5 Put the missing words 1) There are many applications of Newton’s first law ____. 2) Consider some of your ____in an automobile. 3) Coffee “keeps on___ what it is____.” 4) Seat belts are used to provide safety for ___whose motion is governed by Newton’s laws. 5) There are many more ____ of Newton’s first law of motion.

LESSON 19 Active vocabulary Acceleration – ус­ко­ре­ние Force – си­ла Magnitude – ве­ли­чи­на Direction – нап­рав­ле­ние Statement – заяв­ле­ние Equation – урав­не­ния

Rearranged – пе­ре­ст­роен­ный Familiar – зна­ко­мый Below – н ­ и­же entire discussion – все об­суж­де­ние emphasis – ак­цент Cognitive scientists – ког­ни­ти­вис­ты

Text 19 Newton’s second law Newton’s second law of motion can be formally stated as follows: The acceleration of an object produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

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110 Introduction to the World of Physics This verbal statement can be expressed in equation form as follows: a = Fnet / m The above equation is often rearranged to a more familiar form shown below. The net force is equated to the product of the mass times the acceleration. Fnet = m • a In this entire discussion, the emphasis has been on the net force. The acceleration is directly proportional to the net force; the net force equals mass times acceleration; the acceleration in the same direction as the net force; an acceleration is produced by a net force. The NET FORCE. It is important to remember this distinction. Do not use the value of merely “any force” in the above equation. It is the net force that is related to acceleration. The net force is the vector sum of all the forces. If all the individual forces acting upon an object are known, then the net force can be determined.  According to the above equation, a unit of force is equal to a unit of mass times a unit of acceleration. By substituting standard metric units for force, mass, and acceleration into the above equation, the following unit equivalency can be written. 1 Newton = 1 kg • m/s2 The definition of the standard metric unit of force is stated by the above equation. One Newton is defined as the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s. Learning ≠ Storing Cognitive scientists (scientists who study how people learn) have shown that physics students come into physics class with a set of beliefs that they are unwilling (or not easily willing) to discard despite evidence to the contrary. These beliefs about motion (known as misconceptions) hinder further learning. The task of overcoming misconceptions involves self-reflection (to ponder your own belief systems), critical thinking (to analyze the reasonableness of two competing ideas), and evaluation (to select the most reasonable and

Lesson 19

harmonious model that explains the world of motion). While this process may seem terribly complicated, it is simply a matter of using your brain. The most common misconception is one that dates back for ages; it is the idea that sustaining motion requires a continued force. This misconception sticks out its ugly head in a number of different ways and at a number of different times. As your read through the following discussion, give careful attention to your own belief systems. View physics as a system of thinking about the world rather than information that can be dumped into your brain without evaluating its consistency with your own belief systems. Newton’s laws declare loudly that a net force (an unbalanced force) causes an acceleration; the acceleration is in the same direction as the net force. To test your own belief system, consider the following question. Task № 1 Answer the following questions 1) What is the acceleration? 2) What is the unbalanced force? 3) What is the second law of Newton about ? 4) Can you give examples on the second law of Newton? 5) Can you explain a formula of the second law of Newton? Task № 2 Make questions to the underlined words 1) The acceleration of an object produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. 2) The above equation is often rearranged to a more familiar form shown below. 3) The net force is equated to the product of the mass times the acceleration. 4) By substituting standard metric units for force, mass, and acceleration into the above equation, the following unit equivalency can be written. 5) View physics as a system of thinking about the world rather than information that can be dumped into your brain without evaluating its consistency with your own belief systems.

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112 Introduction to the World of Physics Task №3 Find the equivalents to the following words in the text and make up sentences with them: The acceleration, force, magnitude, object, mass, idea, statement. Task № 4 Put definite or indefinite articles 1) The acceleration _ _ object produced _ _ net force _ directly proportional _ _ magnitude _ _ net force, in the same direction _ the net force, and inversely proportional _ the mass _ the object. 2) The above equation _ often rearranged _ _more familiar form shown below. 3) The acceleration _ directly proportional _ the net force; the net force equals mass times acceleration; the acceleration _the same direction _ the net force; _ acceleration _ produced _ _net force. 4) If all the individual forces acting upon _object are known, then the net force can be determined. 5) One Newton _ defined _the amount of force required to give _1-kg mass _ acceleration of 1 m/s/s. Task № 5 Put the missing words 1) The____ of an object produced by a net force is directly proportional to the magnitude of the net force, in the same ____ as the net force, and inversely proportional to the mass of the object. 2) This verbal statement can be ___in equation form as follows. 3) The above ____is often rearranged to a more familiar form shown below. 4) In this entire____, the emphasis has been on the ___. 5) One Newton is defined as the amount of ___required to give a 1-kg mass an acceleration of 1 m/s/s.

LESSON 20 Active vocabulary arising – воз­ни­кающий influences – воз­ни­кает direction – нап­рав­ле­ние opposite – про­ти­во­по­лож­ный action – дей­ст­вие

reaction – реак­ция force – си­ла acceleration – ус­ко­ре­ние outcome – ре­зуль­тат

Lesson 20

Text 20 Newton’s Third Law A force is a push or a pull that acts upon an object as a result of its interaction with another object. Forces result from interactions! Some forces result from contact interactions (normal, frictional, tensional, and applied forces are examples of contact forces) and other forces are the result of action-at-a-distance interactions (gravitational, electrical, and magnetic forces). According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. There are two forces resulting from this interaction – a force on the chair and a force on your body. These two forces are called action and reaction forces and are the subject of Newton’s third law of motion. Formally stated, Newton’s third law is: For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs – equal and opposite action-reaction force pairs.  Examples of Interaction Force Pairs A variety of action-reaction force pairs are evident in nature. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the water. Since forces result from mutual interactions, the water must also be pushing the fish forward propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backward) is opposite the direction of the force on the fish (forward). For every action, there is an equal (in size) and opposite (in direction) reaction force. Action-reaction force pairs make it possible for fish to swim. Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. Since forces result from

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114 Introduction to the World of Physics mutual interactions, the air must also be pushing the bird upwards. The force acting on the air is equal to the force acting on the bird; the direction of the force acting on the air (downwards) is opposite to the direction of the force acting on the bird (upwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Actionreaction force pairs make it possible for birds to fly. Consider the motion of a car on the way to school. A car is equipped with wheels that spin. As the wheels spin, they grip the road and push the road backwards. Since forces result from mutual interactions, the road must also be pushing the wheels forward. The size of the force on the road equals the size of the force on the wheels (or car); the direction of the force on the road (backwards) is opposite the direction of the force on the wheels (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for cars to move along a roadway surface. Task № 1 Answer the following questions 1. What does Newton’s third law specify? 2. Which action forces does your body have when you sit on a chair? 3. What is a consequence of the interaction? 4. What is the size of the forces on the first object? 5. How many are resulting from that interaction? Task № 2 Put questions to the underlined words 1. A variety of action-reaction force pairs are evident in nature. Consider the propulsion of a fish through the water 2. According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. 3. Consider the flying motion of birds. 4. As the wheels spin, they grip the road and push the road backwards. 5. For every action, there is an equal (in size) and opposite (in direction) reaction.

Lesson 21 Task №3 Find the equivalents to the following words in the text and make up sentences with them For instance, fish, backwards., A, uses its fins to, water, push Task №4 Give explanations for the following words: applied physics, telescope, discovery, civilization, stone age, quest, environmental degradation, physical properties, greenhouse gases. Task № 5 Complete with the missing words 1. Consider the motion of a _ on the way to school. 2. A bird flies by _of its wings. 3. Since forces result from_ interactions, the air must also be pushing the bird upwards. 4. A variety of action-reaction force _are evident in nature. 5. As the wheels spin, they grip the road and push the road backwards. Task № 6 Put questions to the text

LESSON 21 Active vocabulary Thermodynamics – тер­мо­ди­на­ми­ка Difference – раз­ность Body – те­ло Trend – тен­ден­ция Difference – раз­ность

Equip – ос­на­щать Occur – проис­хо­дить Object – объект Balance – рав­но­ве­сие Isolation – изо­ля­ция

Text 21 The Zeroth Law of Thermodynamics A temperature difference between two locations will cause a flow of heat along a (thermally) conducting path between those two locations.

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116 Introduction to the World of Physics As long as the temperature difference is maintained, a flow of heat will occur. This flow of heat continues until the two objects reach the same temperature. Once their temperatures become equal, they are said to be at thermal equilibrium and the flow of heat no longer takes place. This principle is sometimes referred to as the zeroth law of thermodynamics. This principle became formalized into a law after the first, second and third laws of thermodynamics had already been discovered. But because the law seemed more fundamental than the previously discovered three, it was titled the zeroeth law. All objects are governed by this law – this tendency towards thermal equilibrium. It represents a daily challenge for those who wish to control the temperature of their bodies, their food, their drinks and their homes. We use ice and insulation to try to keep our cold drinks cold and we use insulation and ongoing pulses of microwave energy to keep our hot drinks hot. We equip our vehicles, our homes and our office buildings equipped with air conditioners and fans in order to keep them cool during the warm summer months. And we equip these same vehicles and buildings with furnaces and heaters in order to keep them warm during the cold winter months. Whenever any of these systems are at a different temperature as the surroundings and not perfectly insulated from the surroundings (an ideal situation), heat will flow. This heat flow will continue until the system and surroundings have achieved equal temperatures. Because these systems have a considerably smaller volume than the surroundings, there will be a more noticeable and substantial change in temperature of these systems. Task 1 Complete missing the words 1) A temperature difference_ two locations will cause a flow of heat along a (thermally) conducting path between those two locations. 2) This flow of heat _until the two objects reach the same temperature. 3) This principle is sometimes referred to as the _law of thermodynamics. 4) But because the law seemed more fundamental than the previously discovered three, it_ titled the zeroeth law. 5) Because these systems have a considerably smaller volume than the surroundings_ _ be a more noticeable and substantial change in temperature of these systems.

Task 2 Answer the following questions 1) What objects are adjusted online? 2) How long did heat flux continue? 3) Did we equip our vehicles, our homes and our office buildings with air? 4) What is the flow temperature? Task 3 Find in the text of the following verbs and emphasize them cause-вы­зы­вать supported-под­дер­жи­вать­ся occur-проис­хо­дить continue-про­дол­жаться reach-дос­ти­гать talk-го­во­рить catch up-срав­няться call-на­зы­вать representant-предс­тов­лять to be-быть Task 4 Find definitions 1. Temperature 2. thermodynamics 3. trend 4. amount A) quantitative characterization of the space occupied by a body or substance B) scalar physical quantity that characterizes the state of thermodynamic equilibrium macroscopic system C) the possibility of certain events develop in this direction D) the branch of physics that studies the relations and the conversion of heat and other forms of energy. Task 5 Make an offer: use,we,ice,insulation,and,keep,try,to,to,cold,our,cold,drin ks,and,insulation,and,use,we,pulses,ongoing,of,microwave,not,energy,to,kee p,drinks,hot,our

118 Introduction to the World of Physics LESSON 22 Vectors and directions A study of motion involves introduction of a variety of quantities that are used to describe the physical world. Examples of such quantities include distance, displacement, speed, velocity, acceleration, force, mass, momentum, energy, work, power, etc. All these quantities can by divided into two categories – vectors and scalars. A vector quantity is a quantity that is fully described by both magnitude and direction. On the other hand, a scalar quantity is a quantity that is fully described by its magnitude. The emphasis of this unit is to understand some fundamentals about vectors and to apply the fundamentals in order to understand motion and forces that occur in two dimensions. Examples of vector quantities include displacement, velocity, acceleration, and force. Each of these quantities is unique in that a full description of the quantity demands that both a magnitude and a direction are listed. For example, suppose your teacher tells you, «A bag of gold is located outside the classroom. To find it, displace yourself 20 meters». This statement may provide your enough information to pique your interest; yet, there is not enough information included in the statement to find the bag of gold. The displacement required to find the bag of gold has not been fully described. On the other hand, suppose your teacher tells you, «A bag of gold is located outside the classroom. To find it, displace yourself from the center of the classroom door 20 meters in a direction 30 degrees to the west of north». This statement now provides a complete description of the displacement vector – it lists both magnitude (20 meters) and direction (30 degrees to the west of north) relative to a reference or starting position (the center of the classroom door). Vector quantities are not fully described unless both magnitude and direction are listed. Representing Vectors Vector quantities are often represented by scaled vector diagrams. Vector diagrams depict a vector by use of an arrow drawn to scale

Lesson 23

in a specific direction. Vector diagrams were introduced and used to depict the forces acting upon an object. Such diagrams are commonly called as free-body diagrams. An example of a scaled vector diagram is shown in the diagram at the right. The vector diagram depicts a displacement vector. Observe that there are several characteristics of this diagram that make it an appropriately drawn vector diagram. – a scale is clearly listed – a vector arrow (with arrowhead) is drawn in a specified direction. The vector arrow has a head and a tail. – the magnitude and direction of the vector is clearly labeled. In this case, the diagram shows the magnitude is 20 m and the direction is (30 degrees West of North).

LESSON 23 Active vocabulary Wave – вол­на Characteristic – ха­рак­те­рис­ти­ка slinky wave – плав­ная вол­на

particle – час­ти­ца assume – при­ни­мать vibration – виб­ра­ция

Text 23 What is a wave? Waves are everywhere. But what makes a wave a wave? What characteristics, properties, or behaviors are shared by the phenomena that we typically characterize as being a wave? How can waves be described in a manner that allows us to understand their basic nature and qualities? A wave can be described as a disturbance that travels through a medium from one location to another location. Consider a slinky wave

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as an example of a wave. When the slinky is stretched from end to end and is held at rest, it assumes a natural position known as the equilibrium or rest position. The coils of the slinky naturally assume this position, spaced equally far apart. To introduce a wave into the slinky, the first particle is displaced or moved from its equilibrium or rest position. The particle might be moved upwards or downwards, forwards or backwards; but once moved, it is returned to its original equilibrium or rest position. The act of moving the first coil of the slinky in a given direction and then returning it to its equilibrium position creates a disturbance in the slinky. We can then observe this disturbance moving through the slinky from one end to the other. If the first coil of the slinky is given a single back-and-forth vibration, then we call the observed motion of the disturbance through the slinky a slinky pulse. A pulse is a single disturbance moving through a medium from one location to another location. However, if the first coil of the slinky is continuously and periodically vibrated in a back-and-forth manner, we would observe a repeating disturbance moving within the slinky that endures over some prolonged period of time. The repeated and periodic disturbance that moves through a medium from one location to another is referred to as a wave.

Task № 1 Answer the following questions: 1) What does a wave make? 2) How can wave be described? 3) Is a slinky wave example of wave? 4) What is the first particle to introduce a wave into the slinky?

Task № 2 Make questions to the underlined words. 1) When the slinky is stretched from end to end and is held at rest, it assumes a natural position known as the equilibrium or rest position 2) The act of moving the first coil of the slinky in a given direction and then returning it to its equilibrium position creates a disturbance in the slinky. 3) A pulse is a single disturbance moving through a medium from one location to another location. 4) The repeated and periodic disturbance that moves through a medium from one location to another is referred to as a wave. Task №3 Find the equivalents to the following words in the text and make up sentences with them disturbance, characteristics, position Task №4 Give explanations for the following words: equilibrium, downwards, slinky, moving through. Task № 5 Put definite or indefinite articles 1. ___ pulse is ___ single disturbance moving through a medium from one location to another location. 2. ___wave can be described as __ disturbance that travels through __ medium from one location to another location. Consider ___ slinky wave as __example of a wave. ___ coils of __ slinky naturally assume this position, spaced equally far apart.

122 Introduction to the World of Physics LESSON 24 Active vocabulary medium – ве­ще­ст­во substance – субс­тан­ция, ве­ще­ст­во news media – но­вос­ти мас­со­вой ин­фор­ма­ции

various – раз­нооб­раз­ный, раз­лич­ ный stadium – ста­дия

Text 24 What is a Medium? But what is meant by the word medium? A medium is a substance or material that carries the wave. You have perhaps heard of the phrase news media. The news media refers to the various institutions (newspaper offices, television stations, radio stations, etc.) within our society that carry the news from one location to another. The news moves through the media. The media doesn’t make the news and the media isn’t the same as the news. The news media is merely the thing that carries the news from its source to various locations. In a similar manner, a wave medium is the substance that carries a wave (or disturbance) from one location to another. The wave medium is not the wave and it doesn’t make the wave; it merely carries or transports the wave from its source to other locations. In the case of our slinky wave, the medium through that the wave travels is the slinky coils. In the case of a water wave in the ocean, the medium through which the wave travels is the ocean water. In the case of a sound wave moving from the church choir to the pews, the medium through which the sound wave travels is the air in the room. And in the case of the stadium wave, the medium through which the stadium wave travels is the fans that are in the stadium. Task № 1 Answer the following questions: 1) What is the word medium meant by? 2) Have you ever heard of the phrase news media?

Lesson 24 3) Does the news move through the media? 4) Does the medium wave make the wave? Task № 2 Make questions to the underlined words. 1) The media doesn’t make the news and the media isn’t the same as the news. 2) In a similar manner, a wave medium is the substance that carries a wave (or disturbance) from one location to another. 3) In the case of a sound wave moving from the church choir to the news, the medium through which the sound wave travels is the air in the room. Task №3 Find the equivalents to the following words in the text and make up sentences with them Perhaps, water wave. Task №4 Give explanations for the following words: substance, similar manner, disturbance, water wave. Task № 5 Put definite or indefinite articles 1. In ___similar manner, ___ wave medium is ___ substance that carries ___ wave (or disturbance) from one location to another. 2. In ___case of __water wave in ___ ocean, the medium through which ___ wave travels is ___ ocean water. 3. ____wave medium is not __wave and it doesn’t make___wave; it merely carries or transports ___ wave from its source to other locations. 4. __ news moves through __ media. 5. In ___case of ___ water wave in ___ ocean, __medium through which ___ wave travels is __ocean water.

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124 Introduction to the World of Physics LESSON 25 Thermal Equilibrium In the discussion of the cooling of the coffee mug, the countertop and the air in the kitchen were referred to as the surroundings. It is common in physics discussions of this type to use a mental framework of a system and the surroundings. The coffee mug (and the coffee) would be regarded as the system and everything else in the universe would be regarded as the surroundings. To keep it simple, we often narrow the scope of the surroundings from the rest of the universe to simply those objects that are immediately surrounding the system. Now let’s imagine a third situation. Suppose that a small metal cup of hot water is placed inside a larger Styrofoam cup of cold water. Let’s suppose that the temperature of the hot water is initially 70°C and that the temperature of the cold water in the outer cup is initially 5°C. And let’s suppose that both cups are equipped with thermometers (or temperature probes) that measure the temperature of the water in each cup over the course of time. What do you suppose will happen? When the cold water has done warming and the hot water has done cooling, will their temperatures be the same or different? Will the cold water warm up to a lower temperature than the temperature the hot water cools down to? Fortunately, an experiment that can be done, in fact, has been done on many occasions. The graph below is a typical representation of the results.

As you can see from the graph, the hot water cooled down to approximately 30°C and the cold water warmed up to approximately the same temperature. Heat is transferred from the high temperature

Lesson 25

object (inner can of hot water) to the low temperature object (outer can of cold water). If we designate the inner cup of hot water as the system, then we can say that there is a flow of heat from the system to the surroundings. As long as there is a temperature difference between the system and the surroundings, there is a heat flow between them. The heat flow is more rapid at first as depicted by the steeper slopes of the lines. Over time, the temperature difference between the system and the surroundings decreases and the rate of heat transfer decreases. This is denoted by the gentler slope of the two lines. Eventually, the system and the surroundings reach the same temperature and the heat transfer ceases. It is at this point, that the two objects are said to have reached thermal equilibrium. Exercise 1 Find the word-terms 1. In the discussion of the cooling of the coffee mug, the countertop and the air in the kitchen were referred to as the surroundings. It is common in physics discussions of this type to use a mental framework of a system and the surroundings. The coffee mug (and the coffee) would be regarded as the system and everything else in the universe would be regarded as the surroundings. 2. Now let’s imagine a third situation. Suppose that a small metal cup of hot water is placed inside a larger Styrofoam cup of cold water. Let’s suppose that the temperature of the hot water is initially 70°C and that the temperature of the cold water in the outer cup is initially 5°C. 3. Heat is transferred from the high temperature object (inner can of hot water) to the low temperature object (outer can of cold water). If we designate the inner cup of hot water as the system, then we can say that there is a flow of heat from the system to the surroundings. 4. A temperature difference between two locations will cause a flow of heat along a (thermally) conducting path between those two locations. As long as the temperature difference is maintained, a flow of heat will occur. This flow of heat continues until the two objects reach the same temperature. Once their temperatures become equal, they are said to be at thermal equilibrium and the flow of heat no longer takes place. 5. This principle is sometimes referred to as the zeroth law of thermodynamics. This principle became formalized into a law after the first, second and third laws of thermodynamics had already been discovered. But because the law seemed more fundamental than the previously discovered three, it was titled the zeroeth law.

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126 Introduction to the World of Physics Exercise 2 Put in a/an or the where necessary. 1. Suppose that __ small metal cup of hot water is placed inside __ larger Styrofoam cup of cold water. 2. Fortunately, __ experiment that can be done, in fact, has been done on many occasions. 3. As long as the temperature difference is maintained, __ flow of heat will occur. 4. Whenever any of these systems are at __ different temperature as the surroundings and not perfectly insulated from the surroundings (__ ideal situation), heat will flow. 5. Because these systems have __ considerably smaller volume than the surroundings, there will be __ more noticeable and substantial change in temperature of these systems. Exercise 3 Translate underlined phrasal verbs 1. In the discussion of the cooling of the coffee mug, the countertop and the air in the kitchen were referred to as the surroundings. 2. Suppose that a small metal cup of hot water is placed inside a larger Styrofoam cup of cold water. 3. Heat is transferred from the high temperature object (inner can of hot water) to the low temperature object (outer can of cold water). 4. This principle is sometimes referred to as the zeroth law of thermodynamics. 5. But because the law seemed more fundamental than the previously discovered three, it was titled the zeroeth law. Exercise 4 Put the verbs into the correct form. 1. Now let’s imagine a ___ situation.(three) 2. This principle became ________ into a law after the first, second and third laws of thermodynamics had already been discovered.(formalize) 3. This is _____ by the gentler slope of the two lines.(denote) 4. Because these systems have a considerably _____ volume than the surroundings, there will be a more noticeable and substantial change in temperature of these systems.(small) 5. The coffee mug (and the coffee) would be _____ as the system and everything else in the universe would be regarded as the surroundings. (regard) Exercise 5 Put questions for these sentences 1. In the discussion of the cooling of the coffee mug, the countertop and the air in the kitchen were referred to as the surroundings. It is common

Translate the following texts and make up questions in physics discussions of this type to use a mental framework of a system and the surroundings. 2. Now let’s imagine a third situation. Suppose that a small metal cup of hot water is placed inside a larger Styrofoam cup of cold water. Let’s suppose that the temperature of the hot water is initially 70°C and that the temperature of the cold water in the outer cup is initially 5°C. 3. All objects are governed by this law - this tendency towards thermal equilibrium. It represents a daily challenge for those who wish to control the temperature of their bodies, their food, their drinks and their homes. 4. If we designate the inner cup of hot water as the system, then we can say that there is a flow of heat from the system to the surroundings. As long as there is a temperature difference between the system and the surroundings, there is a heat flow between them. 5. Whenever any of these systems are at a different temperature as the surroundings and not perfectly insulated from the surroundings (an ideal situation), heat will flow. This heat flow will continue until the system and surroundings have achieved equal temperatures.

TRANSLATE THE FOLLOWING TEXTS AND MAKE UP QUESTIONS Kinematics Physics is a mathematical science. The underlying concepts and principles have a mathematical basis. The motion of objects can be described by words. Even a person without a background in physics has a collection of words that can be used to describe moving objects. Words and phrases such as going fast, stopped, slowing down, speeding up, and turning provide a sufficient vocabulary for describing the motion of objects. In physics, we use these words and many more. We will be expanding upon this vocabulary list with words such as distance, displacement, speed, velocity, and acceleration. As we will soon see, these words are associated with mathematical quantities that have strict definitions. The mathematical quantities that are used to describe the motion of objects can be divided into two categories. The quantity is either a vector or a scalar. These two categories can be distinguished from one another by their distinct definitions:

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128 Introduction to the World of Physics – Scalars are quantities that are fully described by a magnitude (or numerical value) alone. – Vectors are quantities that are fully described by both a magnitude and a direction. Distance and displacement are two quantities that may seem to mean the same thing, yet they have distinctly different definitions and meanings. Distance is a scalar quantity that refers to “how much ground an object has covered” during its motion. Displacement is a vector quantity that refers to “how far out of place an object is”; it is the object’s overall change in position. To test your understanding of this distinction, consider the motion depicted in the diagram below. A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North. Even though the physics teacher has walked a total distance of 12 meters, her displacement is 0 meters. During the course of her motion, she has “covered 12 meters of ground” (distance = 12 m). Yet when she finished walking, she is not “out of place”, i.e. there is no displacement for her motion (displacement = 0 m). Displacement, being a vector quantity, must give attention to direction. The 4 meters east cancels the 4 meters west; and the 2 meters south cancels the 2 meters north. Vector quantities such as displacement are direction aware. Scalar quantities such as distance are ignorant of direction. In determining the overall distance traveled by the physics teachers, the various directions of motion can be ignored. Velocity as a Vector Quantity Velocity is a vector quantity that refers to “the rate at which an object changes its position.” Imagine a person moving rapidly – one step forward and one step back – always returning to the original starting position. While this might result in a frenzy of activity, it would result in a zero velocity. As the person always returns to the original position, the motion would never result in a change in position. Since velocity is defined as the rate at which the position changes, this motion results in zero velocity. If a person in motion wishes to maximize his velocity, then that person must make every effort to maximize the amount that he is displaced from his original position. Every step must go into moving of that person further from where he or she started. For certain, the person should never change directions and begin to return to the starting position.

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Velocity is a vector quantity. As such, velocity is direction aware. When evaluating the velocity of an object, one must keep track of direction. It would not be enough to say that an object has a velocity of 55 mph. One must include direction information in order to fully describe the velocity of the object. For instance, you must describe an object’s velocity as being 55 mph, east. This is one of the essential differences between speed and velocity. Speed is a scalar quantity and does not keep track of direction; velocity is a vector quantity and is direction aware. Determining the Direction of the Velocity Vector The task of describing the direction of the velocity vector is easy. The direction of the velocity vector is simply the same as the direction that an object is moving. It would not matter whether the object is speeding up or slowing down. If an object is moving rightwards, then its velocity is described as rightwards. If an object is moving downwards, then its velocity is described as downwards. So an airplane moving towards the west with a speed of 300 mph has a velocity of 300 mph, west. Note that speed has no direction (it is a scalar) and the velocity at any instant is simply the speed value with a direction. Calculating Average Speed and Average Velocity As an object moves, it often undergoes changes in speed. For example, during an average trip to school, there are many changes in speed. Rather than the speed-o-meter maintaining a steady reading, the needle constantly moves up and down to reflect stopping and starting as well as accelerating and decelerating. One instant, the car may be moving at 50 mph and another instant, it might be stopped (i.e., 0 mi/hr). Yet during the trip to school the person might average 32 mph. The average speed during an entire motion can be thought of as the average of all speedometer readings. If the speedometer readings could be collected at 1-second intervals and then averaged together, the average speed could be determined.   The average speed during the course of a motion is often computed using the following formula: Average Speed =

Distance Traveled Time of Travel

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130 Introduction to the World of Physics In contrast, the average velocity is often computed using this formula Average Velocity =

∆ position displacement = time time

Let’s begin implementing our understanding of these formulas with the following problem: Q: While on vacation, Lisa Carr traveled a total distance of 440 miles. Her trip took 8 hours. What was her average speed? To compute her average speed, we simply divide the distance of travel by the time of travel. v=

d 440 mi = = 55 mi/hr t 8 hr

That was easy! Lisa Carr averaged a speed of 55 miles per hour. She may not have been traveling at a constant speed of 55 mph. She, undoubtedly, stopped at some instant in time (perhaps for a bathroom break or for lunch) and she probably was going 65 mph at other instants in time. Yet, she averaged a speed of 55 miles per hour. The above formula represents a shortcut method of determining the average speed of an object. Average Speed versus Instantaneous Speed Since a moving object often changes its speed during its motion, it is common to distinguish between the average speed and the instantaneous speed. The distinction is as follows. – Instantaneous Speed is the speed at any given instant in time. – Average Speed is the average of all instantaneous speeds found simply by a distance/time ratio. You might think of the instantaneous speed as the speed that the speedometer reads at any given instant in time and the average speed as the average of all the speedometer readings during the course of the trip. The structure of matter There is a large overlap of the world of static electricity and the everyday world that you experience. Clothes tumble in the dryer

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and cling together. You walk across the carpeting to exit a room and receive a door knob shock. You pull a wool sweater off at the end of the day and see sparks of electricity. During the dryness of winter, you step out of your car and receive a car door shock as you try to close the door. Sparks of electricity are seen as you pull a wool blanket off the sheets of your bed. You stroke your cat’s fur and observe the fur standing up on its end. Bolts of lightning dash across the evening sky during a spring thunderstorm. And most tragic of all, you have a bad hair day. These are all static electricity events – events that can only be explained by an understanding of physics of electrostatics. Not only do electrostatic occurrences permeate the events of everyday life, without the forces associated with static electricity, life as we know it would be impossible. Electrostatic forces – both attractive and repulsive in nature – hold the world of atoms and molecules together in perfect balance. Without this electric force, material things would not exist. Atoms as the building blocks of matter depend upon these forces. And material objects, including us Earthlings, are made of atoms and the acts of standing and walking, touching and feeling, smelling and tasting, and even thinking is the result of electrical phenomena. Electrostatic forces are foundational to our existence. History of Atomic Structure The search for the atom began as a philosophical question. It was the natural philosophers of ancient Greece that began the search for the atom by asking such questions as: What is stuff composed of? What is the structure of material objects? Is there a basic unit from which all objects are made? As early as 400 B.C., some Greek philosophers proposed that matter is made of indivisible building blocks known as atomos. (Atomos in Greek means indivisible.) According to these early Greeks, matter could not be continuously broken down and divided indefinitely. Rather, there was a basic unit or building block that was indivisible and foundational to its structure. This indivisible building block of which all matter was composed became known as the atom. The early Greeks were simply philosophers. They did not perform experiments to test their theories. In fact, science as an experimental discipline did not emerge as a credible and popular practice until sometime during the 1600s. So the search for the atom remained a philosophical inquiry for a couple of millennia. From the 1600s to

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132 Introduction to the World of Physics the present century, the search for the atom became an experimental pursuit. Several scientists are notable; among them are Robert Boyle, John Dalton, J.J. Thomson, Ernest Rutherford, and Neils Bohr. Boyle’s studies (middle to late 1600s) of gaseous substances promoted the idea that there were different types of atoms known as elements. Dalton (early 1800s) conducted a variety of experiments to show that different elements can combine in fixed ratios of masses to form compounds. Dalton subsequently proposed one of the first theories of atomic behavior that was supported by actual experimental evidence. English scientist J.J. Thomson’s cathode ray experiments (end of the 19th century) led to the discovery of the negatively charged electron and the first ideas of the structure of these indivisible atoms. Thomson proposed the Plum Pudding Model, suggesting that an atom’s structure resembles the favorite English dessert – plum pudding. The raisins dispersed amidst the plum pudding are analogous to negatively charged electrons immersed in a sea of positive charge. Nearly a decade after Thomson, Ernest Rutherford’s famous gold foil experiments led to the nuclear model of atomic structure. Rutherford’s model suggested that the atom consisted of a densely packed core of positive charge known as the nucleus surrounded by negatively charged electrons. While the nucleus was unique to the Rutherford atom, even more surprising was the proposal that an atom consisted mostly of empty space. Most mass was packed into the nucleus that was abnormally small compared to the actual size of the atom.

Neils Bohr improved upon Rutherford’s nuclear model (1913) by explaining that the electrons were present in orbits outside the nucleus.

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The electrons were confined to specific orbits of fixed radius, each characterized by its own discrete levels of energy. While electrons could be forced from one orbit to another orbit, they could never occupy the space between orbits. Bohr’s view of quantized energy levels was the precursor to modern quantum mechanical views of the atoms. Quantum mechanics suggests that an atom is composed of a variety of subatomic particles. The three main subatomic particles are the proton, electron and neutron. The proton and neutron are the most massive of the three subatomic particles; they are located in the nucleus of the atom, forming the dense core of the atom. The proton is charged positively. The neutron does not possess a charge and is said to be neutral. The protons and neutrons are bound tightly together within the nucleus of the atom. Outside the nucleus are concentric spherical regions of space known as electron shells. The shells are the home of the negatively charged electrons. Each shell is characterized by a distinct energy level. Outer shells have higher energy levels and are characterized as being lower in stability. Electrons in higher energy shells can move down to lower energy shells; this movement is accompanied by the release of energy. Similarly, electrons in lower energy shells can be induced to move to the higher energy outer shells by the addition of energy to the atom. If provided sufficient energy, an electron can be removed from an atom and be freed from its attraction to the nucleus.

Application of Atomic Structure to Static Electricity This brief excursion into the history of atomic theory leads to some important conclusions about the structure of matter that will be of utmost importance to our study of static electricity. These conclusions are summarized as:

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134 Introduction to the World of Physics – All material objects are composed of atoms. There are different kinds of atoms known as elements; these elements can combine to form compounds. Different compounds have distinctly different properties. Material objects are composed of atoms and molecules of these elements and compounds, thus providing different materials with different electrical properties. – An atom consists of a nucleus and a vast region of space outside the nucleus. Electrons are present in the region of space outside the nucleus. They are negatively charged and weakly bound to the atom. Electrons are often removed from and added to an atom. – The nucleus of the atom contains positively charged protons and neutral neutrons. These protons and neutrons are not removable or perturbable by usual everyday methods. It would require some form of high-energy nuclear occurrence to disturb the nucleus and subsequently dislodge its positively charged protons. Electrostatic phenomena can never be explained by the movement of protons. Summary of Subatomic Particles Proton

Neutron

Electron

In nucleus Tightly Bound Positive Charge Massive

In nucleus Tightly Bound No Charge Massive

Outside nucleus Weakly Bound Negative Charge Not very massive

  Inducing the Movement of Charge An atom consists of positively charged protons and negatively charged electrons. The protons are in the nucleus of the atom, tightly bound and incapable of movement. The electrons are located in the vast regions of space surrounding the nucleus, known as the electron shells or the electron clouds. Relative to the protons of the nucleus, these electrons are loosely bound. In conducting objects, they are so loosely bound that they may be induced into moving from one portion of the object to another portion of the object. To get an electron in a conducting object to get up and go, all that must be done is to place a charged object nearby the conducting object.

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To illustrate this induced movement of electrons, we will consider an aluminum pop can that is taped to a Styrofoam cup. The Styrofoam cup serves as both an insulating stand and a handle. A rubber balloon is charged negatively, perhaps by rubbing it against animal fur. If the negatively charged balloon is brought near the aluminum pop can, the electrons within the pop can will experience a repulsive force. The repulsion will be greatest for those electrons that are nearest the negatively charged balloon. Many of these electrons will be induced into moving away from the repulsive balloon. Being present within a conducting material, the electrons are free to move from atom to atom. As such, there is a mass migration of electrons from the balloon’s side of the aluminum can towards the opposite side of the can. This electron movement leaves atoms on the balloon’s side of the can with a shortage of electrons; they become positively charged. And the atoms on the side opposite of the can have an excess of electrons; they become negatively charged. The two sides of the aluminum pop can have opposite charges. The can is electrically neutral; it’s just that the positive and negative charge has been separated from each other. We say that the charge in the can has been polarized.

In the context of electricity, polarization is the process of separating opposite charges within an object. The positive charge becomes separated from the negative charge. By inducing the movement of electrons within an object, one side of the object is left with an excess of positive charge and the other side of the object is left with an excess of negative charge. Charge becomes separated into opposites. The polarization process always involves the use of a charged object to induce electron movement or electron rearrangement. In the above diagram electrons within a conducting object were induced into moving from the left side of the conducting can to the right sideof the can.

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136 Introduction to the World of Physics How Can an Insulator be Polarized? Polarization can occur within insulators, but the process occurs in a different manner than it does within a conductor. In a conducting object, electrons are induced into movement across the surface of the conductor from one side of the object to the opposite side. In an insulator, electrons merely redistribute themselves within the atom or molecules nearest the outer surface of the object. To understand the electron redistribution process, it is important to take another brief excursion into the world of atoms, molecules and chemical bonds. The electrons surrounding the nucleus of an atom are believed to be located in regions of space with specific shapes and sizes. The actual size and shape of these regions is determined by the highpowered mathematical equations common to Quantum Mechanics. Rather than being located a specific distance from the nucleus in a fixed orbit, the electrons are simply thought of as being located in regions often referred to as electron clouds. At any given moment, the electron is likely to be found at some location within the cloud. The electron clouds have varying density; the density of the cloud is considered to be greatest in the portion of the cloud where the electron has the greatest probability of being found at any given moment. And conversely, the electron cloud density is least in the regions where the electron is least likely to be found. In addition to having varying density, these electron clouds are also highly distortable. The presence of neighboring atoms with high electron affinity can distort the electron clouds around atoms. Rather than being located symmetrically about the positive nucleus, the cloud becomes asymmetrically shaped. As such, there is a polarization of the atom as the centers of positive and negative charge are no longer located in the same location. The atom is still a neutral atom; it has just become polarized.

 

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The discussion becomes even more complex (and perhaps too complex for our purposes) when we consider molecules – combination of atoms bonded together. In molecules, atoms are bonded together as protons in one atom attract the electrons in the clouds of another atom. This electrostatic attraction results in a bond between the two atoms. Electrons are shared by the two atoms as they begin to overlap their electron clouds. If the atoms are of different types (for instance, one atom is Hydrogen and the other atom is Oxygen), then the electrons within the clouds of the two atoms are not equally shared by the atoms. The clouds become distorted, with the electrons having the greatest probability of being found closest to the more electron-greedy atom. The bond is said to be a polar bond. The distribution of electrons within the cloud is shifted more towards one atom than towards the other atom. This is the case for the two hydrogen-oxygen bonds in the water molecule. Electrons shared by these two atoms are drawn more towards the oxygen atom than towards the hydrogen atom. Subsequently, there is a separation of charge, with oxygen having a partially negative charge and hydrogen having a partially positive charge. It is very common to observe this polarization within molecules. In molecules that have long chains of atoms bonded together, there are often several locations along the chain or near the ends of the chain that have polar bonds. This polarization leaves the molecule with areas that have a concentration of positive charges and other areas with a concentration of negative charges. This principle is utilized in the manufacture of certain commercial products that are used to reduce static cling. The centers of positive and negative charge within the product are drawn to excess charge residing on the clothes. There is a neutralization of the static charge buildup on the clothes, thus reducing their tendency to be attracted to each other. (Other products actually use a different principle. During manufacturing, a thin sheet is soaked in a solution containing positively charged ions. The sheet is tossed into the dryer with the clothes. Being saturated with positive charges, the sheet is capable of attracting excess electrons that are scuffed off of clothes during the drying cycle.)  

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138 Introduction to the World of Physics How Does Polarization Explain the Balloon and the Wall Demonstration? A complete discussion of the world of atoms, molecules and chemical bonds is beyond the scope of The Physics Classroom. Nonetheless, a model of the atom as a distortable cloud of negative electrons surrounding a positive nucleus becomes essential to understanding how an insulating material can be polarized. If a charged object is brought near an insulator, the charges on that object are capable of distorting the electron clouds of the insulator atoms. There is a polarization of the neutral atoms. As shown in the diagrams below, the neutral atoms of the insulator will orient themselves in such a manner as to place the more attractive charge nearest the charged object. Once polarized in this manner, opposites can now attract.  

A common demonstration performed in class involved bringing a negatively charged balloon near a wooden door or wooden cabinet. The molecules of wood will reorient themselves in such a way as to place their positive charges towards the negatively charged balloon. The distortion of their electron clouds will result in an alignment of the wood molecules in a manner that makes the wooden cabinet attracted to the negatively charged balloon. In human terms, one might say that the wood does some quick grooming and then places its most attractive side towards the balloon and its most repulsive side away from the balloon. In the world of static electricity, closeness counts. The negative balloon is closer to the positive portion of the wood molecules and further from the more repulsive negative

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portion. The balloon and the wall attract with sufficient force to cause the balloon to stick to the wall. From a mechanics standpoint, we would say that the balloon and the wall are pressed together with a large force. The large normal force on the balloon results in a large static friction force. This friction force balances the downward force of gravity and the balloon remains at rest. Another common physics (and chemistry) demonstration involves using a charged object to deflect a stream of water from its path. Most often, a comb is charged negatively by combing one’s hair or a rubber balloon is charged in a similar manner. The negatively charged object is then brought near to a falling stream of water, causing the stream to be attracted to the comb or balloon and alter its direction of fall. The demonstration illustrates the polar nature of water molecules. The hydrogen atoms serve as the positive poles within a water molecule; oxygen serves as the negative pole. Molecules of a liquid are free to rotate and move about; the water molecules realign themselves in order to put their positive poles towards the negatively charged object. Once polarized, the stream and the balloon (or comb) are attracted. As the water molecules within the stream fall past the balloon, this realignment of individual molecules happens quickly and the entire stream is deflected from its original downward direction.

  Examples of the attraction between charged objects and neutral objects are numerous and often demonstrated by physics teachers. Paper bits become polarized and are attracted to a charged piece of acetate. Small penguins cut from a sheet of paper are attracted to a charged plastic golf tube and demonstrate their happy feet. A long

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140 Introduction to the World of Physics wooden 2x4 is placed on a pivot and becomes polarized and attracted to a charged golf tube. To the astonishment of students, the force of attraction on the wood is large enough to rotate it about the pivot point.   Polarization is Not Charging Perhaps the biggest misconception that pertains to polarization is the belief that polarization involves the charging of an object. Polarization is not charging! When an object becomes polarized, there is simply a redistribution of the centers of positive and negative charges within the object. Either by the movement of electrons across the surface of the object (as is the case in conductors) or through the distortion of electron clouds (as is the case in insulators), the of electron clouds (as is the case in insulators), the centers of positive and negative charges become separated from each other. The atoms at one location on the object possess more protons than electrons and the atoms at another location have more electrons than protons. While there are the same number of protons and electrons within the object, these protons and electrons are not distributed in the same proportion across the object’s surface. Yet, there are still equal numbers of positive charges (protons) and negative charges (electrons) within the object. While there is a separation of charge, there is NOT an imbalance of charge. When neutral objects become polarized, they are still neutral objects. The Electrophorus A commonly used lab activity that demonstrates the induction charging method is the Electrophorus Lab. In this lab, a flat plate of foam is rubbed with animal fur in order to impart a negative charge to the foam. Electrons are transferred from the animal fur to the more electron-loving foam (Diagram i.). An aluminum pie plate is taped to a Styrofoam cup; the aluminum is a conductor and the Styrofoam serves as an insulating handle. As the aluminum plate is brought near, electrons within the aluminum are repelled by the negatively charged foam plate. There is a mass migration of electrons to the rim of the aluminum pie plate. At this point, the aluminum pie plate is polarized, with the negative charge located along the upper rim farthest from the foam plate (Diagram ii.). The rim of the plate is then touched,

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providing a pathway from the aluminum plate to the ground. Electrons along the rim are not only repelled by the negative foam plate, they are also repelled by each other. So once touched, there is a mass migration of electrons from the rim to the person touching the rim (Diagram iii.). Being of much greater size than the aluminum pie plate, the person provides more space for the mutually repulsive electrons. The moment that electrons depart from the aluminum plate, the aluminum can be considered a charged object. Having lost electrons, the aluminum possesses more protons than electrons and is therefore positively charged. Once the foam plate is removed, the excess positive charge becomes distributed about the surface of the aluminum plate in order to minimize the overall repulsive forces between them (Diagram iv.).

The Electrophorus Lab further illustrates that when charging a neutral object by induction, the charge imparted to the object is opposite that of the object used to induce the charge. In this case, the foam plate was negatively charged and the aluminum plate became positively charged. The lab also illustrates that there is never a transfer of electrons between the foam plate and the aluminum plate. The aluminum plate becomes charged by a transfer of electrons to the ground. Finally, one might note that the role of the charged object in induction charging is to simply polarize the object being charged. This polarization occurs as the negative foam plate repels electrons from the near side, inducing them to move to the opposite side of the aluminum plate. The presence of the positive charge on the bottom of the aluminum plate is the result of the departure of electrons from that location. Protons did not move downwards through the aluminum. The protons were always there from the beginning; it’s just that they have lost their electron partners. Protons are fixed in place and incapable of moving in any electrostatic experiment.

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142 Introduction to the World of Physics The Electroscope Another common lab experience that illustrates the induction charging method is the Electroscope Lab. In the Electroscope Lab, a positively charged object such as an aluminum pie plate is used to charge an electroscope by induction. An electroscope is a device that is capable of detecting the presence of a charged object. It is often used in electrostatic experiments and demonstrations in order to test for charge and to deduce the type of charge present on an object. There are all kinds of varieties and brands of electroscope from the gold leaf electroscope to the needle electroscope. While there are different types of electroscopes, the basic operation of each is the same. The electroscope typically consists of a conducting plate or knob, a conducting base and either a pair of conducting leaves or a conducting needle. Since the operating parts of an electroscope are all conducting, electrons are capable of moving from the plate or knob on the top of the electroscope to the needle or leaves in the bottom of the electroscope. Objects are typically touched to or held nearby the plate or knob, thus inducing the movement of electrons into the needle or the leaves (or from the needle/leaves to the plate/knob). The gold leaves or needle of the electroscope are the only mobile parts. Once an excess of electrons (or a deficiency of electrons) is present in the needle or the gold leaves, there will be a repulsive affect between like charges causing the leaves to repel each other or the needle to be repelled by the base that it rests upon. Whenever this movement of the leaves/needle is observed, one can deduce that an excess of charge either positive or negative – is present there. It is important to note that the movement of the leaves and needle never directly indicate the type of charge on the electroscope; it only indicates that the electroscope is detecting a charge.

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Suppose a needle electroscope is used to demonstrate induction charging. An aluminum pie plate is first charged positively by the process of induction (see discussion above). The aluminum plate is then held above the plate of the electroscope. Since the aluminum pie plate is not touched to the electroscope, the charge on the aluminum plate is NOT conducted to the electroscope. Nonetheless, the aluminum pie plate does have an affect upon the electrons in the electroscope. The pie plate induces electrons within the electroscope to move. Since opposites attract, a countless number of negatively charged electrons are drawn upwards towards the top of the electroscope. Having lost numerous electrons, the bottom of the electroscope has a temporarily induced positive charge. Having gained electrons, the top of the electroscope has a temporarily induced negative charge (Diagram ii. below). At this point the electroscope is polarized; however, the overall charge of the electroscope is neutral. The charging step then occurs as the bottom of the electroscope is touched to the ground. Upon touching the bottom of the electroscope, electrons enter the electroscope from the ground. One explanation of their entry is that they are drawn into the bottom of the electroscope by the presence of the positive charge at the bottom of the electroscope. Since opposites attract, electrons are drawn towards the bottom of the electroscope (Diagram iii.). As electrons enter, the needle of the electroscope is observed to return to the neutral position. This needle movement is the result of negative electrons neutralizing the previously positively charged needle at the bottom of the electroscope. At this point, the electroscope has an overall negative charge. The needle does not indicate this charge because the excess of electrons is still concentrated in the top plate of the electroscope; they are attracted to the positively charged aluminum pie plate that is held above the electroscope (Diagram iv.). Once the aluminum pie plate is pulled away, the excess of electrons in the electroscope redistribute themselves about the conducting parts of the electroscope. As they do, numerous excess electrons enter the needle and the base upon which the needle rests. The presence of excess negative charged in the needle and the base causes the needle to deflect, indicating that the electroscope has been charged (Diagram v.). The above discussion provides one more illustration of the fundamental principles regarding induction charging. These fundamental principles have been illustrated in each example of induction charging discussed on this page. The principles are:

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144 Introduction to the World of Physics

– The charged object is never touched to the object being charged by induction. – The charged object does not transfer electrons to or receive electrons from the object being charged. – The charged object serves to polarize the object being charged. – The object being charged is touched by a ground; electrons are transferred between the ground and the object being charged (either into the object or out of it). – The object being charged ultimately receives a charge that is opposite that of the charged object that is used to polarize it. Lightning Perhaps the most known and powerful display of electrostatics in nature is a lightning storm. Lightning storms are inescapable from humankind’s attention. They are never invited, never planned and never gone unnoticed. The rage of a lightning strike will wake a person in the middle of the night. They send children rushing into parent’s bedrooms, crying for assurance that everything will be safe. The fury of a lightning strike is capable of interrupting midday conversations and activities. They’re the frequent cause of canceled ball games and golf outings. Children and adults alike crowd around windows to watch the lightning displays in the sky, standing in awe of the power of static discharges. Indeed, a lightning storm is the most powerful display of electrostatics in nature. In this part of Lesson 4, we will ponder two questions: – What is the cause and mechanism associated with lightning strikes? – How do lightning rods serve to protect buildings from the devastating effects of a lightning strike?

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Static Charge Buildup in the Clouds The scientific community has long pondered the cause of lightning strikes. Even today, it is the subject of a good deal of scientific research and theorizing. The details of how a cloud becomes statically charged are not completely understood (as of this writing). Nonetheless there are several theories that make a good deal of sense and that demonstrate many concepts previously discussed in this unit of The Physics Classroom. The precursor of any lightning strike is the polarization of positive and negative charges within a storm cloud. The tops of the storm clouds are known to acquire an excess of positive charge and the bottoms of the storm clouds acquire an excess of negative charge. Two mechanisms seem important to the polarization process. One mechanism involves a separation of charge by a process that bears resemblance to frictional charging. Clouds are known to contain countless millions of suspended water droplets and ice particles moving and whirling about in turbulent fashion. Additional water from the ground evaporates, rises upward and forms clusters of droplets as it approaches a cloud. This upwardly rising moisture collides with water droplets within the clouds. In the collisions, electrons are ripped off the rising droplets, causing a separation of negative electrons from a positively charged water droplet or a cluster of droplets. The second mechanism that contributes to the polarization of a storm cloud involves a freezing process. Rising moisture encounters cooler temperatures at higher altitudes. These cooler temperatures cause the cluster of water droplets to undergo freezing. The frozen particles tend to cluster more tightly together and form the central regions of the cluster of droplets. The frozen portion of the cluster of rising moisture becomes negatively charged and the outer droplets acquire a positive charge. Air currents within the clouds can rip the outer portions off the clusters and carry them upward toward the top of the clouds. The frozen portion of the droplets with their negative charge tends to gravitate towards the bottom of the storm clouds. Thus, the clouds become further polarized. These two mechanisms are believed to be the primary causes of the polarization of storm clouds. In the end, a storm cloud becomes polarized with

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146 Introduction to the World of Physics positive charges carried to the upper portions of the clouds and negative portions gravitating towards the bottom of the clouds. The polarization of the clouds has an equally important effect on the surface of the Earth. The cloud’s electric field stretches through the space surrounding it and induces movement of electrons upon Earth. Electrons on Earth’s outer surface are repelled by the negatively charged cloud’s bottom surface. This creates an opposite charge on the Earth’s surface. Buildings, trees and even people can experience a buildup of static charge as electrons are repelled by the cloud’s bottom. With the cloud polarized into opposites and with a positive charge induced upon Earth’s surface, the stage is set for Act 2 in the drama of a lightning strike.   The Mechanics of a Lightning Strike As the static charge buildup in a storm cloud increases, the electric field surrounding the cloud becomes stronger. Normally, the air surrounding a cloud would be a good enough insulator to prevent a discharge of electrons to Earth. Yet, the strong electric fields surrounding a cloud are capable of ionizing the surrounding air and making it more conductive. The ionization involves the shredding of electrons from the outer shells of gas molecules. The gas molecules that compose air are thus turned into a soup of positive ions and free electrons. The insulating air is transformed into a conductive plasma. The ability of a storm cloud’s electric fields to transform air into a conductor makes charge transfer (in the form of a lightning bolt) from the cloud to the ground (or even to other clouds) possible. A lightning bolt begins with the development of a step leader. Excess electrons on the bottom of the cloud begin a journey through the conducting air to the ground at speeds up to 60 miles per second. These electrons follow zigzag paths towards the ground, branching at various locations. The variables that affect the details of the actual pathway are not well known. It is believed that the presence of impurities or dust particles in various parts of the air might create regions between clouds and earth that are more conductive than other regions. As the step leader grows, it might be illuminated by the purplish glow that is characteristic of ionized air molecules. Nonetheless, the step leader is not the actual lightning strike; it merely provides the roadway between cloud and Earth along which the lightning bolt will eventually travel. As the electrons of the step leader approach the Earth, there is an additional repulsion of electrons downward from Earth’s surface. The quantity of positive charge residing on the Earth’s surface becomes

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even greater. This charge begins to migrate upward through buildings, trees and people into the air. This upward rising positive charge – known as a streamer – approaches the step leader in the air above the surface of the Earth. The streamer might meet the leader at an altitude equivalent to the length of a football field. Once contact is made between the streamer and the leader, a complete conducting pathway is mapped out and the lightning begins. The contact point between ground charge and cloud charge rapidly ascends upward at speeds as high as 50 000 miles per second. As many as a billion trillion electrons can transverse this path in less than a millisecond. This initial strike is followed by several secondary strikes or charge surges in rapid succession. These secondary surges are spaced apart so closely in time that may appear as a single strike. The enormous and rapid flow of charge along this pathway between the cloud and Earth heats the surrounding air, causing it to expand violently. The expansion of the air creates a shockwave that we observe as thunder.   Lightning Rods and Other Protective Measures Tall buildings, farmhouses and other structures susceptible to lightning strikes are often equipped with lightning rods. The attachment of a grounded lightning rod to a building is a protective measure that is taken to protect the building in the event of a lightning strike. The concept of a lightning rod was originally developed by Ben Franklin. Franklin proposed that lightning rods should consist of a pointed metal pole that extends upward above the building that it is intended to protect. Franklin suggested that a lightning rod protects a building by one of two methods. First, the rod serves to prevent a charged cloud from releasing a bolt of lightning. And second, the lightning rod serves to safely divert the lightning to the ground in event that the cloud does discharge its lightning via a bolt. Franklin’s theories on the operation of lightning rods have endured for a couple of centuries. And not until the most recent decades have scientific studies provided evidence to confirm the manner in which they operate to protect buildings from lightning damage.

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148 Introduction to the World of Physics The first of Franklin’s two proposed theories is often referred to as the lightning dissipation theory. According to the theory, the use of a lightning rod on a building protects the building by preventing the lightning strike. The idea is based upon the principle that the electric field strength is great around a pointed object. The intense electric fields surrounding a pointed object serve to ionize the surrounding air, thus enhancing its conductive ability. The dissipative theory states that as a storm cloud approaches, there is a conductive pathway established between the statically charged cloud and the lightning rod. According to the theory, static charges gradually migrate along this pathway to the ground, thus reducing the likelihood of a sudden and explosive discharge. Proponents of the lightning dissipation theory argue that the primary role of a lightning rod is to discharge the cloud over a longer length of time, thus preventing the excessive charge buildup that is characteristic of a lightning strike. The second of Franklin’s proposed theories on the operation of the lightning rod is the basis of the lightning diversion theory. The lightning diversion theory states that a lighting rod protects a building by providing a conductive pathway of the charge to the Earth. A lightning rod is typically attached by a thick copper cable to a grounding rod that is buried in the Earth below. The sudden discharge from the cloud would be drawn towards the elevated lightning rod but safely directed to the Earth, thus preventing damage from occurring to the building. The lightning rod and the attached cable and ground pole provide a low resistance pathway from the region above the building to the ground below. By diverting the charge through the lightning protection system, the building is spared of the damage associated with a large quantity of electric charge passing through it. Lightning researchers are now generally convinced that the lightning dissipation theory provides an inaccurate model of how lightning rods work. It is indeed true that the tip of a lightning rod is capable of ionizing the surrounding air and making it more conductive. However, this effect only extends for a few meters above the tip of the lightning rod. A few meters of enhanced conductivity above the tip of

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the rod is not capable of discharging a large cloud that stretches over several kilometers of distance. Unfortunately, there are currently no scientifically verified methods of lightning prevention. Furthermore, recent field studies have further shown that the tip of the lightning rod does not need to be sharply pointed as Ben Franklin suggested. Blunttipped lightning rods have been found to be more receptive to lightning strikes and thus provide a more likely path of discharge of a charged cloud. When installing a lightning rod on a building as a lightning protection measure, it is imperative that the rod be elevated above the building and connected by a low resistance wire to the ground. Conventional Current Direction The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction in which positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field. But while electrons are the charge carriers in metal wires, the charge carriers in other circuits can be positive charges, negative charges or both. In fact, the charge carriers in semiconductors, street lamps and fluorescent lamps are simultaneously both positive and negative charges traveling in opposite directions. Ben Franklin, who conducted extensive scientific studies in both static and current electricity, envisioned positive charges as the carriers of charge. As such, an early convention for the direction of an electric current was established to be in the direction that positive charges would move. The convention has stuck and is still used today. The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction. Knowing that the actual charge carriers in wires are negatively charged electrons may make this convention seem a bit odd and outdated. Nonetheless, it is the convention that is used worldwide and one that a student of physics can easily become accustomed to.    Current versus Drift Speed Current has to do with the number of coulombs of charge that pass a point in the circuit per unit of time. Because of its definition, it is

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150 Introduction to the World of Physics often confused with the quantity drift speed. Drift speed refers to the average distance traveled by a charge carrier per unit of time. Like the speed of any object, the drift speed of an electron moving through a wire is the distance to time ratio. The path of a typical electron through a wire could be described as a rather chaotic, zigzag path characterized by collisions with fixed atoms. Each collision results in a change in direction of the electron. Yet because of collisions with atoms in the solid network of the metal conductor, there are two steps backwards for every three steps forward. With an electric potential established across the two ends of the circuit, the electron continues to migrate forward. Progress is always made towards the positive terminal. Yet the overall effect of the countless collisions and the high betweencollision speeds is that the overall drift speed of an electron in a circuit is abnormally low. A typical drift speed might be 1 meter per hour. That is slow! One might then ask: How can there by a current on the order of 1 or 2 ampere in a circuit if the drift speed is only about 1 meter per hour? The answer is: there are many, many charge carriers moving at once throughout the whole length of the circuit. Current is the rate at which charge crosses a point on a circuit. A high current is the result of several coulombs of charge crossing over a cross section of a wire on a circuit. If the charge carriers are densely packed into the wire, then there does not have to be a high speed to have a high current. That is, the charge carriers do not have to travel a long distance in a second, there just has to be a lot of them passing through the cross section. Current does not have to do with how far charges move in a second but rather with how many charges pass through a cross section of wire on a circuit. To illustrate how densely packed the charge carriers are, we will consider a typical wire found in household lighting circuits – a 14-gauge copper wire. In a 0.01 cm-long (very thin) cross-sectional slice of this wire, there would be as many as 3.51 x 1020 copper atoms. Each copper atom has 29 electrons; it would be unlikely that even the 11 valence electrons would be in motion as charge carriers at once. If we assume that each copper atom contributes just a single electron, then there would be as much as 56 coulombs of charge within a thin 0.01-cm length of the wire. With that much mobile charge within such

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a small space, a small drift speed could lead to a very large current. To further illustrate this distinction between drift speed and current, consider this racing analogy. Suppose that there was a very large turtle race with millions and millions of turtles on a very wide race track. Turtles do not move very fast – they have a very low drift speed. Suppose that the race was rather short – say 1 meter in length – and that a large percentage of the turtles reached the finish line at the same time – 30 minutes after the start of the race. In such a case, the current would be very large – with millions of turtles passing a point in a short amount of time. In this analogy, speed has to do with how far the turtles move in a certain amount of time; and current has to do with how many turtles cross the finish line in a certain amount of time. The Nature of Charge Flow Once it has been established that the average drift speed of an electron is very, very slow, the question soon arises: Why does the light in a room or in a flashlight light appear immediately after the switch is turned on? Wouldn’t there be a noticeable time delay before a charge carrier moves from the switch to the light bulb filament? The answer is NO! and the explanation of “why” reveals a significant amount about the nature of charge flow in a circuit. As mentioned above, charge carriers in the wires of electric circuits are electrons. These electrons are simply supplied by the atoms of copper (or whatever material the wire is made of) within the metal wire. Once the switch is turned to on, the circuit is closed and an electric potential difference is established across the two ends of the external circuit. The electric field signal travels at nearly the speed of light to all mobile electrons within the circuit, ordering them to begin marching. As the signal is received, the electrons begin moving along a zigzag path in their usual direction. Thus, the flipping of the switch causes an immediate response throughout every part of the circuit, setting charge carriers everywhere in motion in the same net direction. While the actual motion of charge carriers occurs with a slow speed, the signal that informs them to start moving travels at a fraction of the speed of light. The electrons that light the bulb in a flashlight do not have to travel from the switch through 10 cm of wire to the filament. Rather, the electrons that light the bulb immediately after the switch is turned to on are the electrons that are present in the filament itself. As the switch is flipped, all mobile electrons everywhere begin marching; and it is the mobile electrons present in the filament whose motion is

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152 Introduction to the World of Physics immediately responsible for the lighting of its bulb. As those electrons leave the filament, new electrons enter and become the ones that are responsible for lighting the bulb. The electrons are moving together much like the water in the pipes of a home moves. When a faucet is turned on, it is the water in the faucet that emerges from the spigot. One does not have to wait a noticeable time for water from the entry point to your home to travel through the pipes to the spigot. The pipes are already filled with water and water everywhere within the water circuit is set in motion at the same time. The picture of charge flow is a picture in which charge carriers are like soldiers marching along together, everywhere at the same rate. Their marching begins immediately in response to the establishment of an electric potential across the two ends of the circuit. There is no place in the electrical circuit where charge carriers become consumed or used up. While the energy possessed by the charge may be used up (or it is better to say that the electric energy is transformed into other forms of energy), the charge carriers themselves do not disintegrate, disappear or otherwise become removed from the circuit. And there is no place in the circuit where charge carriers begin to pile up or accumulate. The rate at which charge enters the external circuit on one end is the same as the rate at which charge exits the external circuit on the other end. The Sinusoidal Nature of Pendulum Motion Let’s suppose that we could measure the distance that the pendulum bob is displaced to the left or to the right of its equilibrium or rest position over the course of time. A displacement to the right of the equilibrium position would be regarded as a positive displacement; and a displacement to the left would be regarded as a negative displacement.

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Using this reference frame, the equilibrium position would be regarded as the zero position. And suppose that we constructed a plot showing the variation in position with respect to time. The resulting position vs. time plot is shown below. The position of the pendulum bob (measured along the arc relative to its rest position) is a function of the sine of time.

Now suppose that we use our motion detector to investigate how the velocity of the pendulum changes with respect to time. As the pendulum bob does the back and forth, the velocity is continuously changing. There will be times at which the velocity is a negative value (for moving leftward) and other times at which it will be a positive value (for moving rightward). And there will be moments in time at which the velocity is 0 m/s. If the variations in velocity over the course of time were plotted, the resulting graph would resemble the one shown below.

Now let’s try to understand the relationship between the position of the bob along the arc of its motion and the velocity with which it moves. Suppose we identify several locations along the arc and then relate these positions to the velocity of the pendulum bob.

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The plot above is based upon the equilibrium position (D) being designated as the zero position. A displacement to the left of the equilibrium position is regarded as a negative position. A displacement to the right is regarded as a positive position. An analysis of the plots shows that the velocity is the least when the displacement is the greatest. And the velocity is the greatest when the displacement of the bob is the least. The further the bob has moved away from the equilibrium position, the slower it moves; and the closer the bob is to the equilibrium position, the faster it moves. This can be explained by the fact that as the bob moves away from the equilibrium position, there is a restoring force that opposes its motion. This force slows the bob down. Energy Analysis Let us o associate the motion characteristics described above with the concepts of kinetic energy, potential energy and total mechanical energy. The kinetic energy possessed by an object is the energy it possesses due to its motion. It is a quantity that depends upon both mass and speed. The equation that relates kinetic energy (KE) to mass (m) and speed (v) is KE = ½•m•v2

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The faster an object moves, the more kinetic energy that it will possess. We can combine this concept with the discussion above about how speed changes during the course of motion. The kinetic energy of the pendulum bob increases as the bob approaches the equilibrium position. And the kinetic energy decreases as the bob moves further away from the equilibrium position.

The potential energy possessed by an object is the stored energy of position. Elastic potential energy is only present when a spring (or other elastic medium) is compressed or stretched. A simple pendulum does not consist of a spring. The form of potential energy possessed by a pendulum bob is gravitational potential energy. The amount of gravitational potential energy depends on the mass (m) of the object and the height (h) of the object. The equation for gravitational potential energy (PE) is PE = m•g•h where g represents the gravitational field strength (sometimes referred to as the acceleration caused by gravity) and has the value of 9.8 N/kg. The height of an object is expressed relative to some arbitrarily assigned zero level. In other words, the height must be measured as a vertical distance above some reference position. For a pendulum bob, it is customary to call the lowest position the reference position or the zero level. So when the bob is at the equilibrium position (the lowest position), its height is zero and its potential energy is 0 J. As

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156 Introduction to the World of Physics the pendulum bob does back and forth, there are times during which the bob is moving away from the equilibrium position. As it does, its height is increasing as it moves further and further away. It reaches a maximum height as it reaches the position of maximum displacement from the equilibrium position. As the bob moves towards its equilibrium position, it decreases its height and decreases its potential energy. Now let’s put these two concepts of kinetic energy and potential energy together as we consider the motion of a pendulum bob moving along the arc shown in the diagram at the right. We will use an energy bar chart to represent the changes in the two forms of energy. The amount of each form of energy is represented by a bar. The height of the bar is proportional to the amount of that form of energy. In addition to the potential energy (PE) bar and kinetic energy (KE) bar, there is a third bar labeled TME. The TME bar represents the total amount of mechanical energy possessed by the pendulum bob. The total mechanical energy is simply the sum of the two forms of energy – kinetic plus potential energy.

When you inspect the bar charts, it is evident that as the bob moves from A to D, the kinetic energy is increasing and the potential energy is decreasing. However, the total amount of these two forms of energy is remaining constant. Whatever potential energy is lost in going from position A to position D appears as kinetic energy. There is a transformation of potential energy into kinetic energy as the bob moves from position A to position D. Yet the total mechanical energy remains constant. We would say that mechanical energy is conserved. As the bob moves past position D towards position G, the opposite is observed. Kinetic energy decreases as the bob moves rightward and (more importantly) upward toward position G. There is an increase in potential energy to accompany this decrease in kinetic energy. Energy is being transformed from kinetic form into potential form. Yet, as illustrated by the TME bar, the total amount of mechanical energy is conserved.

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Overview of semiconductors Semiconductors are very similar to insulators. The two categories of solids differ primarily in that insulators have larger band gaps–energies that electrons must acquire to be free to flow. In semiconductors at room temperature, just as in insulators, very few electrons gain enough thermal energy to leap the band gap, which is necessary for conduction. For this reason, pure semiconductors and insulators, in the absence of applied fields, have roughly similar electrical properties. The smaller bandgaps of semiconductors, however, allow for many other means besides temperature to control their electrical properties. Semiconductors’ intrinsic electrical properties are very often permanently modified by introducing impurities, in a process known as doping. Usually it is reasonable to approximate that each impurity atom adds one electron or one «hole» that may flow freely. Upon the addition of a sufficiently large proportion of dopants, semiconductors conduct electricity nearly as well as metals. The junctions between regions of semiconductors that are doped with different impurities contain built-in electric fields, which are critical to semiconductor device operation. In addition to permanent modification through doping, the electrical properties of semiconductors are often dynamically modified by applying electric fields. The ability to control conductivity in small and well-defined regions of semiconductor material, statically through doping and dynamically through the application of electric fields, has led to the development of a broad array of semiconductor devices, like transistors. Semiconductor devices with dynamically controlled conductivity are the building blocks of integrated circuits, like the microprocessor. These «active» semiconductor devices are combined with simpler passive components, such as semiconductor capacitors and resistors, to produce a variety of electronic devices. In certain semiconductors, when electrons fall from the conduction band to the valence band (the energy levels above and below the band gap), they often emit light. This photoemission process underlies the light-emitting diode (LED) and the semiconductor laser, both of which are tremendously important commercially. Conversely, semiconductor absorption of light in photodetectors excites electrons from the valence band to the conduction band, facilitating reception of fiber optic communications, and providing the basis for energy from solar cells.

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158 Introduction to the World of Physics Semiconductors may be elemental materials, such as silicon, compound semiconductors such as gallium arsenide, or alloys, such as silicon germanium or aluminium gallium arsenide. History of semiconductor device development 1900s Semiconductors had been used in the electronics field for some time before the invention of the transistor. Around the turn of the twentieth century they were quite common as detectors in radios, used in a device called a «cat’s whisker.» These detectors were somewhat troublesome, however, requiring the operator to move a small tungsten filament (the whisker) around the surface of a galena (lead sulfide) or carborundum (silicon carbide) crystal until it suddenly started working. Then, over a period of a few hours or days, the cat‘s whisker would slowly stop working and the process would have to be repeated. At the time their operation was completely mysterious. After the introduction of the more reliable and amplified vacuum tube based radios, the cat’s whisker systems quickly disappeared. The «cat’s whisker» is a primitive example of a special type of diode still popular today, called a Schottky diode. World War II During World War II, radar research quickly pushed radar receivers to operate at ever higher frequencies and the traditional tube based radio receivers no longer worked well. The introduction of the cavity magnetron from Britain to the United States in 1940 during the Tizzard Mission resulted in a pressing need for a practical high-frequency amplifier. Russell Ohl of Bell Laboratories decided to try a cat’s whisker. By this point they had not been in use for a number of years, and no one at the labs had one. After hunting one down at a used radio store in Manhattan, he found that it worked much better than tube-based systems. Ohl investigated why the cat’s whisker functioned so well. He spent most of 1939 trying to grow more pure versions of the crystals. He soon found that with higher quality crystals their finicky behavior went away, but so did their ability to operate as a radio detector. One day he found one of his purest crystals nevertheless worked well, and interestingly, it had a clearly visible crack near the middle. However as he moved about the room trying to test it, the detector would mysteriously work, and then stop again. After some study he

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found that the behaviour was controlled by the light in the room–more light caused more conductance in the crystal. He invited several other people to see this crystal, and Walter Brattain immediately realized there was some sort of junction at the crack. Further research cleared up the remaining mystery. The crystal had cracked because either side contained very slightly different amounts of the impurities Ohl could not remove–about 0.2 percent. One side of the crystal had impurities that added extra electrons (the carriers of electrical current) and made it a «conductor.» The other had impurities that wanted to bind to these electrons, making it (what he called) an «insulator.» Because the two parts of the crystal were in contact with each other, the electrons could be pushed out of the conductive side which had extra electrons (soon to be known as the emitter) and replaced by new ones being provided (from a battery, for instance) where they would flow into the insulating portion and be collected by the whisker filament (named the collector). However, when the voltage was reversed the electrons being pushed into the collector would quickly fill up the «holes» (the electron-needy impurities), and conduction would stop almost instantly. This junction of the two crystals (or parts of one crystal) created a solid-state diode, and the concept soon became known as semiconduction. The mechanism of action when the diode is off has to do with the separation of charge carriers around the junction. This is called a «depletion region.» Development of the transistor After the war, William Shockley decided to attempt the building of a triode-like semiconductor device. The key to the development of the transistor was the further understanding of the process of the electron mobility in a semiconductor. It was realized that if there was some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, one could build an amplifier. For instance, if you placed contacts on either side of a single type of crystal, the current would not flow through it. However, if a third contact could then «inject» electrons or holes into the material, the current would flow. Actually doing this appeared to be very difficult. If the crystal were of any reasonable size, the number of electrons (or holes) required to be injected would have to be very large–making it less than useful as an amplifier because it would require a large injection current to

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160 Introduction to the World of Physics start with. That said, the whole idea of the crystal diode was that the crystal itself could provide the electrons over a very small distance, the depletion region. The key appeared to be to place the input and output contacts very close together on the surface of the crystal on either side of this region. Brattain started working on building such a device, and tantalizing hints of amplification continued to appear as the team worked on the problem. Sometimes the system would work but then stopped working unexpectedly. In one instance a non-working system started working when placed in water. Ohl and Brattain eventually developed a new branch of quantum mechanics known as surface physics to account for the behavior. The electrons in any one piece of the crystal would migrate about due to nearby charges. Electrons in the emitters, or the «holes» in the collectors, would cluster at the surface of the crystal where they could find their opposite charge «floating around» in the air (or water). Yet they could be pushed away from the surface with the application of a small amount of charge from any other location on the crystal. Instead of a large supply of injected electrons, a very small number in the right place on the crystal would accomplish the same thing. The first transistor A stylized replica of the first transistor invented at Bell Labs in 1947.

The Bell team made many attempts to build such a system with various tools, but generally failed. Setups where the contacts were close enough were invariably as fragile as the original cat’s whisker detectors had been, and would work briefly, if at all. Eventually they had a practical breakthrough. A piece of gold foil was glued to the

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edge of a plastic wedge, and then the foil was sliced with a razor at the tip of the triangle. The result was two very closely spaced contacts of gold. When the plastic was pushed down onto the surface of a crystal and voltage applied to the other side (on the base of the crystal), current started to flow from one contact to the other as the base voltage pushed the electrons away from the base towards the other side near the contacts. The point-contact transistor had been invented. While the device was constructed a week earlier, Brattain’s notes describe the first demonstration to higher-ups at Bell Labs on the afternoon of December 23, 1947, often given as the birth date of the transistor. The «PNP point-contact germanium transistor» operated as a speech amplifier with a power gain of 18 in that trial. Known generally as a point-contact transistor today, John Bardeen, Walter Houser Brattain, and William Bradford Shockley were awarded the Nobel Prize in physics for their work in 1956. Origin of the term «transistor» Bell Telephone Laboratories needed a generic name for their new invention: «Semiconductor Triode,» «Solid Triode,» «Surface States Triode,» «Crystal Triode» and «Iotatron» were all considered, but «transistor,» coined by John R. Pierce, won an internal ballot. The rationale for the name is described in the following extract from the company’s Technical Memoranda (May 28, 1948) calling for votes: Transistor. This is an abbreviated combination of the words «transconductance» or «transfer,» and «varistor.» The device logically belongs in the varistor family, and has the transconductance or transfer impedance of a device having gain, so that this combination is descriptive. Improvements in transistor design Shockley was upset about the device being credited to Brattain and Bardeen, who he felt had built it «behind his back» to take the glory. Matters became worse when Bell Labs lawyers found that some of Shockley’s own writings on the transistor were close enough to those of an earlier 1925 patent by Julius Edgar Lilienfeld that they thought it best that his name be left off the patent application. Shockley was incensed, and decided to demonstrate who was the real brains of the operation. Only a few months later he invented an entirely new type of transistor with a layer or ‘sandwich’ structure. This new form was considerably more robust than the fragile point-

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162 Introduction to the World of Physics contact system, and would go on to be used for the vast majority of all transistors into the 1960s. It would evolve into the bipolar junction transistor. With the fragility problems solved, a remaining problem was purity. Making germanium of the required purity was proving to be a serious problem, and limited the number of transistors that actually worked from a given batch of material. Germanium’s sensitivity to temperature also limited its usefulness. Scientists theorized that silicon would be easier to fabricate, but few bothered to investigate this possibility. Gordon Teal was the first to develop a working silicon transistor, and his company, the nascent Texas Instruments, profited from its technological edge. Germanium disappeared from most transistors by the late 1960s. Within a few years, transistor-based products, most notably radios, were appearing on the market. A major improvement in manufacturing yield came when a chemist advised the companies fabricating semiconductors to use distilled water rather than tap water: calcium ions were the cause of the poor yields. «Zone melting,» a technique using a moving band of molten material through the crystal, further increased the purity of the available crystals. Semiconductor device materials By far, silicon (Si) is the most widely used material in semiconductor devices. Its combination of low raw material cost, relatively simple processing, and a useful temperature range make it currently the best compromise among the various competing materials. Silicon used in semiconductor device manufacturing is currently fabricated into boules that are large enough in diameter to allow the production of 300 mm (12 in.) wafers. Germanium (Ge) was a widely used early semiconductor material but its thermal sensitivity makes it less useful than silicon. Today, germanium is often alloyed with silicon for use in very-high-speed SiGe devices; IBM is a major producer of such devices. Gallium arsenide (GaAs) is also widely used in high-speed devices but so far, it has been difficult to form large-diameter boules of this material, limiting the wafer diameter to sizes significantly smaller than silicon wafers thus making mass production of GaAs devices significantly more expensive than silicon.

CONTENTS

Lesson 1..........................................................................................3 Lesson 2..........................................................................................8 Lesson 3........................................................................................14 Lesson 4........................................................................................20 Lesson 5........................................................................................26 Lesson 6........................................................................................32 Lesson 7........................................................................................36 Lesson 8........................................................................................47 Lesson 9........................................................................................57 Lesson 10......................................................................................61 Lesson 11......................................................................................67 Lesson 12......................................................................................74 Lesson 13......................................................................................76 Lesson 14......................................................................................80 Lesson 15......................................................................................88 Lesson 16......................................................................................95 Lesson 17....................................................................................102 Lesson 18....................................................................................106 Lesson 19....................................................................................109 Lesson 20....................................................................................112 Lesson 21....................................................................................115 Lesson 22....................................................................................118 Lesson 23....................................................................................119 Lesson 24....................................................................................122 Lesson 25....................................................................................124 Translate the following texts and make up questions................................................................127

Еducational issue

Strautman Lidya Evgenievna Gumarova Sholpan Bilashevna Sabyrbaeva Nazigul Kusainovna INTRODUCTION TO THE WORLD OF PHYSICS Teaching manual

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IB No. 8120

Signed for publishing 07.04.2015. Format 60x84 1/16. Offset paper. Digital printing. Volume 10,25 printer’s sheet. 120 copies. Order No 713. Publishing house «Qazaq university» Al-Farabi Kazakh National University KazNU, 71 Al-Farabi, 050040, Almaty Printed in the printing office of the «Qazaq university» publishing house