A quantity of heat Q=6.0×103J is removed from a hot reservoir at 500K and finally deposited in a cold reservoir at 300K. Consider the following two alternative paths for the heat transfer, both carried out without doing any work:
Path A: Direct transfer of the whole Q from 500K to 300K.
Path B: First transfer Q from 500K to an intermediate reservoir at 400K, and then transfer the same Q from 400K to 300K. All reservoirs are so large that their temperatures remain constant.
(a) Calculate the entropy change of the universe for Path A.
(b) Calculate the entropy change of the universe for Path B.
(c) Which path is closer to a reversible transfer? Justify your answer by comparing the numerical values obtained.