Page 147 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

iii. Reaumur Scale : The freezing point of water at normal atmospheric pressure is 0° and boiling point is 80 °.
The difference between 0 to 80 is equally divided into 80 parts each part is called as 1°R.

Scale Freezing point Boiling point
Centigrade (°C) 0°C 100°C
Fahrenheit (°F) 32°F 212°F
Kelvin (K) 273°K 373°K

Reaumur (°R) 0°R 80°R

(i) Heat is a form of energy.Temperature is the degree of hotness or coldness of a body.
(ii) The relationship for conversion from one temperature scale to the others.

(iii)

Special Properties of mercury for selecting as a medium in a thermometer
Mercury has special properties for selecting as a medium in a thermometer. The following are important advantages
of using mercury in thermometer
1 It does not wet the glass. No mercury is left behind in the tube, as the temperature falls.
ii It is a good conductor of heat and hence quickly attains the temperature of the surrounding body.
iii It has uniform co-efficient of expansion.
iv It remains as a liquid over a wide range of temperature.
v Mercury freezes at 39°C. Hence it is not suitable for measuring low temperatures.

Transmission of Heat
Heat is a form of energy and is capable of doing work. Heat flows from a hot body to a colder body or from a point
of high temperature to a point of low temperature. The greater is the temperature difference the more rapidly will
be the heat flow. Heat is transmitted in three ways.
• By Conduction
• By Convection

• By Radiation

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CITS : WCS - Electrical - Exercise 12