Laws of Thermodynamics

There are four laws of thermodynamics as follows:

• Zeroth law of thermodynamics
• First law of thermodynamics
• Second law of thermodynamics
• Third law of thermodynamics  

 Zeroth law of thermodynamics:

When two systems are each in thermal equilibrium with a third system, then the two systems are also in thermal equilibrium with one another.

First law of Thermodynamics:

• The heat and mechanical work are mutually convertible. 

∮∂Q =∮∂W

• The energy can neither be created nor destroyed through it can be transformed from one form to another. 

 ∂Q-∂W=dE

 

Second law of thermodynamics:

• Kelvin-Plank Statement: It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy from a single thermal reservoir into an equivalent amount of work.
• Clausius Statement: It is impossible for a self acting machine working on a cyclic process, to transfer heat from a body at a lower temperature to a body at a higher temperature without the aid of an external agency.

Third law of thermodynamics:

 

     The entropy of any pure substance is thermodynamics equilibrium approaches zero as the temperature approaches zero.