Why is integration performed under reversible path only?
Answers
Answer:
There are two parts to this answer. The first is that the entropy change is defined only for reversible processes. The second is that the entropy is a state function. Many, but not all, the functions in thermodynamics (including the internal energy) are state functions.
A state function is one that is independent of path. That is, if one goes from state A to state B, the change in internal energy is independent of how the change takes place. The same is true for the entropy.
So the entropy change in going from state A to state B is independent of how the change takes place. But we can calculate the change ONLY for reversible changes.
So we mentally find a reversible path from state A to state B and calculate the entropy change. Since entropy is a state function, that must also be the change for a non-reversible path.
Answer:
Since R2 is a reversible path i RI T R2 *— ic> i *• Since Rl and ^?2 represent ... (7.6) Integration can be performed only on a reversible path. ... 7.6 Area under a reversible path