Answer: Moves heat from cold to hot body using work input.
- A Converts heat completely to work with no external input
- B Moves heat from cold to hot body using work input
- C Permanently destroys heat energy via friction in the compressor
- D Creates a cold region from nothing, violating energy conservation
Correct answer: B. Moves heat from cold to hot body using work input
Explanation: Refrigerator: uses work input to transfer heat from cold body (inside) to hot body (surroundings). It is a heat pump.
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.