Exam-style question
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What is a key limitation of reversed heat engines?.
- A.They can operate indefinitely without energy input.
- B.They cannot transfer heat from a cold to a hot reservoir without work input.
- C.They are always 100% efficient.
- D.They require no maintenance.
Model answer
What a good answer should say
- They cannot transfer heat from a cold to a hot reservoir without work input.
Explanation
Why this works
Reversed heat engines require work input to transfer heat from a cold reservoir to a hot reservoir, which is a fundamental limitation of their operation.
Common mistake
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