Question

A refrigerator operates by a) doing work to move heat from a low-temperature thermal reservoir to a high- temperature thermal reservoir. b) doing work to move heat from a high-temperature thermal reservoir to a low-temperature thermal reservoir. c) using thermal energy to produce useful work. d) moving heat from a low-temperature thermal reservoir to a hightemperature thermal reservoir without doing work. e) moving heat from a high-temperature thermal reservoir to a lowtemperature thermal reservoir without doing work.

Short answer

Answer: A refrigerator operates by doing work to move heat from a low-temperature thermal reservoir (inside) to a high-temperature thermal reservoir (outside).

Step-by-step solution

Understanding the basic principles of refrigeration

A refrigerator is a heat engine that operates in a reversed cycle. Its main purpose is to transfer heat from a cold place (inside the refrigerator) to a warmer place (outside). The refrigerator does this by evaporation and condensation, using a refrigerant fluid which continuously moves through the system.

Analyzing each statement

Let's now analyze each of the provided statements: a) This statement says that the refrigerator does work to move heat from a low-temperature thermal reservoir to a high-temperature thermal reservoir. This matches the description of how a refrigerator functions since it takes the heat from the cold inside and releases it to the warmer outside. b) This statement says that the refrigerator does work to move heat from a high-temperature thermal reservoir to a low-temperature thermal reservoir. This is contrary to the refrigerator operation as it moves heat in the opposite direction. c) This statement says that the refrigerator uses thermal energy to produce useful work. A refrigerator uses work provided by an external source (like electricity) to move heat, not to produce work. d) This statement claims that the refrigerator moves heat from a low-temperature thermal reservoir to a high-temperature thermal reservoir without doing work. This is impossible based on the second law of thermodynamics. Work must be done to transfer heat from a colder to a warmer place. e) This statement claims that the refrigerator moves heat from a high-temperature thermal reservoir to a low-temperature thermal reservoir without doing work. This is also impossible based on the second law of thermodynamics, but it also contradicts the actual operation of a refrigerator as it moves heat from a cold place to a warm place.

Conclusion

Based on our analysis of each statement, we find that statement (a) is the correct description for how a refrigerator operates. A refrigerator does work to move heat from a low-temperature thermal reservoir (inside) to a high-temperature thermal reservoir (outside).