Question

Suppose a Carnot engine can be operated between two reservoirs as either a heat engine or a refrigerator. How is the coefficient of performance of the refrigerator related to the efficiency of the heat engine?

a) They are equal
b) The coefficient of performance is the reciprocal of the efficiency
c) The coefficient of performance is twice the efficiency
d) There is no relationship between them

Answer 1

The coefficient of performance of a refrigerator is the reciprocal of the efficiency of a heat engine.

Step-by-step explanation:

The coefficient of performance (COP) of a refrigerator is related to the efficiency of a heat engine by the equation: COP = 1 / (Efficiency - 1).

So, the correct answer to your question is b) The coefficient of performance is the reciprocal of the efficiency.

For example, if the efficiency of a heat engine is 0.4 (40%), then the COP of a refrigerator operating between the same two reservoirs would be 1 / (0.4 - 1) = 1 / -0.6 = -1.67.