Answer: Qcold/W.
- A W/Qcold
- B Qcold/W
- C Qhot/W
- D W/Qhot
Correct answer: B. Qcold/W
Explanation: COP = Qcold/W (heat removed from cold reservoir per unit work done). A good refrigerator has high COP.
The Carnot cycle alternates two isothermal steps (heat absorbed at TH, released at TC) with two adiabatic steps (no heat exchange); the enclosed loop area equals the net work output, and η = 1−TC/TH is the maximum possible efficiency between those two temperatures.
Concept context
Laws of thermodynamics, heat engines, entropy, and gas processes.