Text 22 В - раздел Образование, Part One THE PREDICATE Прочтите Текст Про Себя (Контрольное Время Чтения—4,5 Минуты). Temperature Sc...
Прочтите текст про себя (контрольное время чтения—4,5 минуты). Temperature Scales
If two objects are placed in contact with one another, thermal energy may flow from one objcct to the other one. Temperature is the quality that determines the direction in which thermal energy flows — it flows from the objcct at higher temperature to the objcct at lower temperature.
Temperatures are ordinarily measured by means of a thermometer, such as the ordinary mcrcuiy thermometer, consisting of a quantity of mercuiy in a glass tube. The temperature scalc used by scientists is the centigrade or Celsius scale; it was introduced by Anders Celsius (1701- 1744), a Swedish professor of astronomy, in 1742. On this scale the
temperature of freezing water saturated with air is 0°C and the temperature of filing water is 100°C at 1-atm pressure.
On the Fahrenheit scale, used in everyday life in English-speaking countries, the freezing point of water is 32°F and the boiling point of water is 212°F. On this scale the freezing point and the boiling point differ by 180°, rather than 100° of the ccntigrade scalc. The Fahrenheit scalc was devised by Gabriel Fahrenheit (1686-1736), a natural philosopher who was born in Danzig and settled in Holland. He invented the mercury thermometer in 1714; before then, alcohol had been used as the liquid in thermometers. As the zero point on his scale he took the lowest temperature he could obtain, produced by mixing equal quantities of snow and ammonium chloride. His choice of 212° for the boiling point of water was made in order that the temperature of his body should be 100°F. The normal temperature of the human body is 98.6°F; perhaps Fahrenheit had a slight fever while he was calibrating his thermometer.
To convert temperatures from one scale to another, you need only remember that the Fahrenheit degree is l(K>/|$o or % of the centigrade degree, and that 0°C is the same temperature as 32°F.
Another absolute scale, the Rankine scale, is sometimes used in engineering work in the English-speaking countries. It uses the Fahrenheit degree, and has 0°R as the absolute zero.
