Question

What does the zeroth law of thermodynamics allow us to define?

Answer 1

It defines that if two thermodynamic systems are each in equilibrium with a third system, then they are in equilibrium with each other.

Answer 2

Explanation :

The Zeroth law gives the concept of thermal equilibrium. Let there are three systems i.e. A, B and C.

According to Zeroth law :

Let us suppose that the system A and B are in thermal equilibrium with each other and also B and C are in thermal equilibrium. Then the system A and C will also be in thermal equilibrium with each other.

Hence, the zeroth law defines the thermal equilibrium within the system.