While dealing with laws of Thermodynamics, it is important to note that there are 2 laws associated with it, and certain theorems are explained mathematically. This Clausius Theorem is associated with Second Law of Thermodynamics and is mathematical explanation. This theorem specifically explains relation between entropy of a system and its heat flow in its surroundings.

This inequality feature is applicable to any real engine cycle and places a negative charge on entropy of the cycle itself. It is also notable that entropy that is given to environment during a cycle greater than the entropy that has been transferred by heat to that engine from the hot reservoir.

**8.5.2 Reversible Isothermal Process**

**8.5.3 Carnot Cycle in T -S Plot**

Process 1 – 2 = reversible isothermal

Process 2- 3 = reversible adiabatic T

Process 3 – 4 = reversible isothermal

Process 4-1 = reversible adiabatic