Question

What do you mean by thermal equilibrium? How does the concept of thermal equilibrium help us to define temperature?

Answer 1

1. As we know that heat flows from higher temperature to lower temperature. When this flow of heat stops, then this state is known as thermal equilibrium.
2. Since thermal equilibrium can be introduced only there is variation of temperature ( measure of hotness or coldness) between the two or more bodies.
3. As thermal equilibrium clearly explains that there is no net heat flow between two bodies means we cannot define which body is hot or cold.
4. Thus if these bodies were not in thermal equilibrium, then there must be heat flow, so what the concept of temperature explains.