The process in which the initial and final state is the same is known as a cyclic process. It is a sequence of processes that leave the system in the same state in which it started.
When a system undergoes a cyclic process, its initial and final internal energies are equal. Hence, the internal energy change in any cyclic process is zero. Applying the first law of thermodynamics to a cyclic process, we get\(\Delta E=Q+W\)
As \(\Delta E=0\),\(W=Q\)
W=0 is not true for cyclic process.
Hence, the work done by the system in a cyclic transformation is equal to the heat absorbed by the system. An example of such a system is a refrigerator or air conditioner.