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Thermodynamics and engines (A-level only)

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Question 8
1.

Which is a correct statement about an ideal heat pump?

  • A. The coefficient of performance (COPhp\text{COP}_{\text{hp}}COPhp​) is less than 1.0 if the temperature difference between the hot and cold reservoirs is very large.
  • B. The COPhp\text{COP}_{\text{hp}}COPhp​ increases as the temperature of the cold reservoir is decreased, keeping the hot reservoir temperature constant.
  • C. A heat pump operating between a cold reservoir at 250 K and a hot reservoir at 300 K has a theoretical maximum coefficient of performance of 6.0.
[1]
2.

An ideal refrigerator has a coefficient of performance COPref\text{COP}_{\text{ref}}COPref​ of 3.0. The same device is run in reverse as an ideal heat engine operating between the same two spaces.

Determine the thermal efficiency η \eta\,η of this heat engine.

[4]

Thermodynamics and engines (A-level only) Questions

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  3. /Thermodynamics and engines (A-level only)