Temperature Measurement

Temperature is the degree of hotness (or coldness) of a body, and can be regarded as a measure of the internal energy contained within the body.

This energy manifests, according to the kinetic theory, by the agitation of the atoms that make up the body. When the internal energy of a body changes, a number of physical changes take place. These may include a change in the volume of the body, thermo-electric e.m.f., electrical resistance and radiation.
Each of these possible changes forms the basis of a temperature measuring device. The most common devices for measuring temperature are:

i. The liquid-in-glass thermometer
ii. The thermocouple
iii. The electrical resistance thermometer
iv. Pyrometers

Good estimates of the temperature of a body can also be made by making use of heat-sensitive paints, crayons and Seger cones.