Question

Mention the significance of Zeroth law.

Answer 1

Hint: Zeroth law is considered under thermodynamic law. Thermal equilibrium is a transitive in nature. Systems which are in thermal equilibrium have the same temperature and vice versa.

Complete answer step by step:
Statement:
Let A, B and C are systems. If thermodynamic systems A and B are in thermal equilibrium with system C then systems A and B are in thermal equilibrium with each other.
Thermal equilibrium means the net amount of heat exchanged is zero. So the net amount of heat exchange between systems A & C and B & C is zero. According to Zeroth law of thermodynamics system A and B are also in thermal equilibrium hence the net amount of heat exchange between these two is also zero. Even though they are not in contact with each other. So this shows the transitive property of thermal equilibrium.

Significance:
This law signifies that temperature is a fundamental indicator of thermal equilibrium. If two bodies of the same temperature come in contact with each other then there is no net exchange of heat and those two bodies are said to be in thermal equilibrium. Conversely if two bodies are in thermal equilibrium then they have the same temperature.

Additional Information:
This law seems very obvious but it is so fundamental that we call it a law. This law is actually named after three laws and it provides very basic fundamentals for other three laws so that it is termed as Zeroth law of thermodynamics.

Note: Zeroth law of thermodynamics is actually an observation. Remember that this law is about thermal equilibrium and thermal equilibrium indicates that systems have the same temperature and conversely systems having same temperature are in thermal equilibrium.