Laws of Thermodynamics

The laws of thermodynamics define fundamental physical quantities such as temperature, energy and entropy that describe thermodynamic systems.

The First Law of Thermodynamics

This law states that the difference between the sum of the heat flowing into a closed system and the work flowing from the system is equal to the increase in the internal energy of the system.

∆U = Q – W

∆U = change in internal energy

Q = heat added to the system

W = work done by the system

The Second Law of Thermodynamics

This law states that it in every natural thermodynamic process, the sum of the entropies of all participating bodies is increased. It is impossible for a heat engine to produce network in a complete cycle if it exchanges heat only with bodies at single fixed temperature.

∆S ≥ 0

∆S = change in entropy