investigation is to determine the best conditions for the reaction.
5. Sometimes wc use icc to
cool the body.
Слова к тексту:
devise — придумать; triple— тройной; saturate — насыщать; hence —
следовательно; convenience — удобство; resistance — сопротивление;
thermocouple— термопара
Text 23 В
Прочтите текст про себя (контрольное время чтения — 4 минуты).
The Kelvin Temperature Scale
and Modern Means of Measuring the Temperature
About 200 years ago scientists noticed that a sample of gas that is
cooled decreases in volume in a regular way, and they saw that if the
volume were to continue to decrease in the same way, it would bccomc
zero at about -273°C. The conccpt was developed that this temperature
-273°C (more accurately -273.15°C) is the minimum temperature, the
absolute zero. A new temperature scalc was then devised by Lord Kelvin,
a great British physicist (1824-1907). The
Kelvin scale is defined in
such a way as to permit the laws of thermodynamics to be expressed in a
simple form.
The International Standard temperature scalc is the Kelvin scalc with
a new definition of the degree. The absolute zero is taken to be OK and the
triple point of water is taken to be 273.1SK. (The
triple point of water, the
temperature at which pure liquid water, icc and water vapour arc in
equilibrium, will be discusscd later.) With this definition of the degree,
the boiling point of water at onc-atmosphcrc pressure is 373.1 SK and the
freezing point of water saturated with air at onc-atmosphcrc pressure is
273.15K. Hence the SI Kelvin temperature is 273.15K greater than the
ccntigradc temperature.
Gas Thermometer
The establishment of the International Temperature Scalc has required
that the thermodynamic temperatures of the fixed points be determined
with as much accuracy as possible. For this purpose a device was needed
that measures essentially the thcmodynamic temperature and docs not
depend on any particular thcrmomctric substancc. On the other hand, sincc
it was needed only for a few highly accurate measurements, it did not
need to have the convenience o f such instruments as resistance
thermometers, mercury thermometers, and thermocouples. The dcvicc that
has filled this need is the
gas thermometer.
Упр. 3. Передайте основное содержание текста в нескольких пред
ложениях.
159
Упр. 4. Составьте план текста.
Упр. 5. Прочтите предложения н скажите, соответствуют ли онн
содержанию текста. Если ист, исправьте их.
1. More than a century ago scientists noticcd the dependence between
the temperature and the volume of a gas. 2. The temperature at which the
volume o f the gas sample would become zero was named the absolute
zero. 3. Hie scalc according to which the absolute zero is taken to be 0° is
the International Standard temperature scalc. 4. The triple
point of water
is the temperature when vapourization begins. 5. The temperature by the
Kelvin scalc is the temperature by Celsius scalc plus 273.15°. 6. Gas
thermometer is used for ordinary measurements. 7. Gas thermometer is a
convenient instrument. 8. This dcvicc is highly accurate.
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язык.
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