Внимательно прочитайте текст за три минуты и назовите имена ученых, открывших закон сохранения энергии.

Слова для понимания текста:

estimate v — оценивать; tension n — напряжение; reconcile ['rekansail] v — примирять

The Law of Energy Conservation

Heat, this most active, powerful and mysterious phenomenon of Nature, was once a really challenging problem to physicists-professionals as well as non-professionals. Among the first investigators of the problem were people of all walks of Же: the peer of France Laplace and the English manufacturer of beer Joule [dju:! ], the French philosopher and writer Voltair and the Eng­lish acrobat, musician and physicist Young, the War Minister Rumford and the French doctor Paul Marat, the leader of the French Revolution.

The first to estimate the mechanical equivalent of heat was Robert May­er (1842). Soon afterwards it was also proposed by Joule and later by von Helmholtz, a physiologist and a physicist. The same idea, though not so clearly expressed, seems to have occurred to at least five other physicists or engineers. The approaches of the three principal discoverers were dif­ferent. Mayer was led to the conception by general philosophical consider­ations of a cosmical kindl He was struck by the analogy between the ener­gy gained by bodies falling under gravity and the heat given off by com­pressed gases. Joule was led to the idea first by experiments aimed at finding out how far the new electric motor could become a practical source of power. Helmholtz in 1847, by an attempt to generalize the Newtonian con­ception of motion to that of a large number of bodies acting under mutual attraction, showed that the sum of force and tension, what we would now call kinetic and potential energy, remained the same. This is the principle of conservation of energy in its most formal sense, but it was important in that it reconciled the new doctrines of heat with the older ones of mechan­ics, a process that was to be largely completed by William Thomson (later Lord Kelvin), a friend of both Joule and Helmholtz, in his paper The Dynamical Equivalent of Heat (1851).

ЗАДАНИЯ К ТЕКСТУ

• Объясните, как вы понимаете выделенные в тексте слова.

• Найдите в тексте ответы на следующие вопросы:

1. What was the difference in the approaches to the problem of heat of the three principal discoverers? 2. What was the contribution of Lord Kelvin into the problem?

(4) Conversation Practice

• Answer the questions on Text 31 A.

1. When did the first speculations about heat begin? 2. Why was heat so important for humanity? 3. What were the early conceptions about heat? 4. What practical experiences supported these ideas? 5. What human activities demanded the development of heat as a quantitative science? 6. What experimental observations enabled Dr. Black to establish specific heat and latent heat? 7. How was this discovery proved in practice? 8. Why was the doctrine of conservation of energy one of the great generalizations and contributions into the physics of the nineteenth century? 9. What does the first law of thermodynamics state? 10. What human activities depend on energy?

• Speak on the following topics:

1. Prometheus [pr9⁽mi: 9j9s] stole fire and brought it to people. Why was it so important?

2. The first conceptions of heat were primitive but helpful. Why?

3. Great discoveries in the field came from experimental practice and not vice versa. Why?

4. Heat and energy. What interrelation is there between them?

5. Industrial processes and heat.

(5) Home Exercises

1. Переведите на английский язык следующие словосочетания:

несвязанные факты, незафиксированные наблюдения; не поддер­жанные практикой идеи; непоглощенное тепло; неусовершенство­ванный двигатель; необъяснимый эффект; не достигнутый на прак­тике КПД; непредусмотренные законы природы

Переведите на русский язык.

1. We know heat to have been a difficult problem to solve. 2. Do you know Galileo to have constructed the first air-expansion thermometer? 3. Aristotle assumed hot and cold to be connected with wet and dry. 4. One knows heat to have been of great importance for the development of industry. 5. The first investigator of heat found different substances to be heated to different degrees by the same amount of coal. 6. We know nineteenth century physics to be great achievement of the human mind.

3. Ответьте на вопросы. Выскажите свое мнение (суждение), упот­ребив глагол, указанный в скобках.

Model I: Does this value change? (expecf)-4Wz expect it to change.

1. Do your friends know physics well? (expect) 2. Do they make physics experiments? (know) 3. Do they take interest in their future speciality? (believe) 4. Will they take exams in physics? (suppose). 5. Will they get good marks in physics? (believe) 6. Will they become investigators soon? (doubt)

Model 2: Have they considered the problem yet? (believe) —> We believe them to have considered it.

7. Has he made the necessary measurements yet? (expect) 8. Have they checked the results yet? (believe) 9. Have they accounted for this effect? (expect) 10. Has this value changed? (assume) 11. Has the platinum plate reached a sufficiently high temperature? (believe) 12. Has she found an answer to this problem? (doubt)

4. Переведите на английский язык, используя Complex Object, 1. Я хочу, чтобы вы рассмотрели этот вопрос сейчас. 2. Он полага­ет, что они скоро завершат работу. 3. Она ожидает, что мы получим хорошие результаты. 4. Мы ожидаем, что вы опишете это подробно. 5. Он заставил меня повторить измерение. 6. Я слышал, что они об­суждали этот вопрос много раз.

(6) Enjoy Yourself

A DISGUSTED GUEST AT A RESTAURANT: You can't expect me to eat this stuff! Call the manager!

WAITER: It's no use; he won't eat it either.

stuff n — дрянь

UNIT 32 (1) Grammar

ИНФИНИТИВ В СОСТАВЕ СЛОЖНОГО ПОДЛЕЖАЩЕГО (COMPLEX SUBJECT WITH THE INFINITIVE)

Мнение (суждение или предположение) группы неопределенных лиц о каком-либо лице (факте или понятии) говорящий на английском языке может выразить двумя способами:

1) сложноподчиненным предложением с придаточным предложе­нием-подлежащим. Например: It is said that this value changes. Изве­стно, что значение меняется. It is expected that she will come tomorrow. Ожидают, что она прибудет завтра.

2) простым предложением со сложным подлежащим, в состав которого входит имя существительное (в общем падеже) или

(2) Word and Phrase Study

1. Английские термины часто представляют собой цепочку, со­стоящую из двух или нескольких существительных, ^ которой ос­новным словом является последнее существительное, а существи­тельные, стоящие перед ним, определяют его.

field чего? -*-

Strength

что? напряженность

• Переведите на русский язык следующие английские термины. Проверьте правильность перевода по ключу.

1. energy source; 2. emission energy, 3. radiation intensity; 4. space radiation intensity; 5. substance surface; 6. surface pressure; 7. research value; 8. energy source research; 9. energy source research value; 10. surface radiation intensity research

2. as far as... is concerned — что касается ... Например: As far as length is concerned, it varies. — Что касается длины, то она изме­няется.

3. other than — кроме, за исключением

(3) Reading 32А

Изучив схему, внимательно прочитайте текст и подумайте, адек­ватно ли схема отражает информацию текста. Какие еще понятия можно было бы ввести в схему?

High temperature incandescent **—

Source of light -

Ultraviolet radiation -fluorescent

Sources of Light

There are different kinds of light sources, some of them are caused by high temperatures, others by some other factors.

Every source of light is known to have a luminous intensity, which is measurable. In general, the higher is the temperature of the source, the greater (is) the luminous intensity of the light it emits. At room temper­ature we see a piece of metal like platinum by the light it reflects. If we heat it until it reaches a sufficiently high temperature, we can see then this piece of platinum even in a darkened room by the light

it emits. Incandescence is the emission of light caused by high temper­atures. To produce light by incandescence, we maintain the object we are using as a source at a high temperature relative to, say, room temperature (about 68°F). Under these conditions a substance be­comes white or bright-red hot and emits light. Certain substances emit light without becoming incandescent; we consider them to be luminescent.

Luminescence is the emission of light from a body from any cause other than high temperature. We consider fluorescence and phospho­rescence to be particular cases of luminescence. A candle flame is an example of incandescence. The light emitted by a firefly (светлячок) is an example of luminescence. Certain substances emit visible light when ultraviolet light shines on them. We know them to be fluo­rescent materials. Experiment shows that ultraviolet radiation of this sort does not increase the temperature of fluorescent substances appre­ciably above room temperature. Light from fluorescent sources is not incandescent.

Almost immediately after an ordinary light bulb has been lit, it is uncomfortably hot to the touch. As far as an ordinary light bulb is con­cerned, it is an incandescent source. A lighted fluorescent lamp is un­likely to be too hot to the touch. It is known to be a luminescent light source. Ultraviolet light shining on zinc sulfide causes it to emit a green light. We know it to be a fluorescent source. As we have already stated, every object which emits light has a measurable luminous intensity. The sun certainly has greater luminous iritensity than an ordinary elec­tric bulb. To measure luminous intensity we have to define a unit. The unit is the standard candle (or more briefly, the candela). A source which has a luminous intensity of 25 candles is 25 times more intense than the candela. We define a standard candle as 1/60 of the luminous inten­sity of the light emitted by 1 cm² of an incandescent platinum metal surface maintained at a fixed temperature 1763°C. One cm² of such a surface has a luminous intensity of 60 (standard) candles. Although we define the standard candle in terms of the luminous intensity of a certain area of incandescent platinum metal surface, we use it to measure the luminous intensity of any luminous object. This means that the luminous intensity of a fluorescent lamp is also measured in a standard candle.

A source of light which is small compared to the area it illuminates is called a point source. An electric bulb illuminating a large auditorium is a point source. A small candle flame has less luminous intensity than the bulb of a large street lamp. A surface placed at equal distances from each of these sources is certain to receive more illumination from the

street lamp. The illumination of a surface is called illuminance and it is the amount of light falling on unit area of the surface per second. The derived unit of illumination in SI system of units is the lux (lumen per square metre). Illuminance is directly proportipnal to the luminous in­tensity of the source. However, it depends not only on the luminous intensity of the source but also on the distance of the illuminated area from the source of light. Illuminance is inversely proportional to the square of the distance from the source.

ЗАДАНИЯ К ТЕКСТУ

• Выпишите из текста английские эквиваленты следующих рус­ских словосочетаний:

по любой причине, кроме; частные случаи; неприятно горяча на ощупь; что касается; в 25 раз интенсивнее; количество света; точеч­ный источник; интенсивность свечения; источник света; на основа­нии интенсивности свечения; обратно пропорциональна; выведен­ная единица

• Употребите подходящие по смыслу слова из предлагаемых в скоб­ках вариантов.

1. We use the standard candle to measure the luminous intensity of (only some I any) luminous objects. 2. A source of light which is (large I small) compared to the area it illuminates is called a point source. 3. Illuminance of a surface is (directly I inversely) proportional to the luminous intensity of the source and (directly I inversely) proportional to the square of the distance from the source. 4. The candle is a unit used to measure (luminous intensity I illuminance) 5. The lux is a unit used to measure (luminous intensity I illuminance) in SI units. 6. All luminous objects emit (the same amount I different amount? ) of light. 7. A source which has a luminous intensity of 25 candles is 25 times (more I less) intense than the standard candle. 8. We define the standard candle in terms of the light emitted by 1 cm² of a(n) (luminescent I incandescent I fluorescent) platinum metal surface maintained at a (random I fixed) temperature.

• Заполните пропуски подходящими по смыслу словами.

1. We see luminous objects by the light they... to the eye. 2. Every source of light has a luminous... which is.... 3. An object we see by the

light it reflects is said to be.... 4. A substance heated until it " glows" and

emits light is said to be.... 5. We see unlit electric bulb because it... light

which some other source of light.... 6. A platinum plate heated to a high

temperature is an...... of.... 7. We see the Moon at night because it...

light which the Sun.....

 

 

Reading 32B

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