Range of different thermometers

Mercury Thermometer: from -30˚C to 350˚C

Constant volume gas thermometer: from -200˚C to 500˚C (with H₂), below -200˚C upto -268˚C (with He) above 1000˚C upto 1600˚C (with N₂ gas and bulb of glazed porcelain)

Platinum resistance thermometer: form -200˚C to 1200˚C

Thermocouple thermometer: form -200˚C to 1600˚C

Total Radiation Pyrometer

When a body is at high temperature, it glows brightly and the radiation emitted by the body is directly proportional to the fourth power of absolute temperature of the body. Radiation pyrometer measures the temperature of a body by measuring the radiation emitted by the body.

This thermometer is not put in contact with the body. But it cannot measure temperature below 800˚C because at low temperature emission of radiation is very small and cannot be detected. 

Specific Heat Capacity: Specific heat capacity of a material is the amount of heat required to raise the temperature of unit mass of substance through 1˚. Its SI unit is Joule/ gram˚C.

1 calorie / gram˚C = 4200 Joule / kg Kelvin.

Thermal Expansion

When a body is heated its length, surface area and volume increase. The increase in length , area and volume with the increase in temperature are measured in terms of coefficient of linear expansion or linear expansively (α) coefficient of superficial expansion or superficial expansively (β) and coefficient of cubical expansion or cubical expansively (γ).

Specific Heat Capacities of different materials (J/kg K)

Water       4200

Ice             2100

Iron              460

K. Oil             210

Mercury     140

Lead            130    

Relation between α, β and γ.

α: β :γ =1:2:3                   or,    β=2   α and  γ =3α