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What is the Zeroth Law of Thermodynamics?

Answer – The zeroth law of thermodynamics states that if two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with one another as well.

Explanation: 

Two objects or systems are said to be in thermal equilibrium if they transfer thermal energy to each other and attain a steady temperature over a period of time.

One of the four laws of thermodynamics, the zeroth law was formulated by scientist Ralph H. Fowler. It illustrates how thermal equilibrium is achieved between 3 systems or objects.

Consider 3 systems X, Y, and Z. According to the zeroth law, if X is in thermal equilibrium with Z and Y is also in thermal equilibrium with Z, then X and Y are in thermal equilibrium with each other.

This law finds many applications in everyday life:

1. Any item when placed in a refrigerator reaches the same temperature as the refrigerator and every other item in it.

2. If you place a block of ice and a glass of hot water in a room, the ice and hot water will eventually reach the temperature of the room and each other.


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