This Lesson explains Second Law of thermodynamics, Heat Engines, Refrigerators, Reversible and Irreversible processes.
The Second Law of Thermodynamics
The second law of thermodynamics asserts that processes occur in a certain direction and that the energy has quality as well as quantity. The first law places no restriction on the direction of a process, and satisfying the first law does not guarantee that the process will occur. Thus, we need another general principle (second law) to identify whether a process can occur or not.