Heat is a form of energy. It derives its origins at the molecular scale. Molecules of a substance vibrate at their positions either fixed or not when energy is supplied to them. As they vibrate they transfer their energy to the surrounding molecules causing them to vibrate as well.

This kinetic energy builds up on a macro level as more and more energy is supplied to these molecules of the substance. As a result, when this energy reaches a threshold ( eg. Melting point, Boiling point) do the molecules or atoms free themselves from interatomic forces of attraction and conversion of a state i.e. phase change takes place.

Heat energy of a body can also be defined as a form of energy that can be transferred from one body to the other or within the body itself with a temperature difference and can be generated by a body at the expense of other forms of energy. The SI unit of heat energy is Joule abbreviated as ‘J’. In CGS system, however, heat is measured in ‘Calorie’ (Cal.) where 1 Calorie = 4.186 J

What is Temperature?

The temperature of a body is the measure of the amount of heat content possessed by it. It is measured in degree Celcius (°C) or Kelvin(°K). The temperature of a substance is a physical quantity that measures the degree of hotness or coldness of a body.

Thermal Properties of Matter

The properties of the matter involving heat transfer and measurement are known as ‘Thermal Properties of Matter’