A Carnot engine operates between reservoirs at 600 K and 300 K. Its maximum possible efficiency is
- A. 20 per cent
- B. 50 per cent
- C. 75 per cent
- D. 100 per cent
Explanation
Carnot efficiency is 1 minus the ratio of the cold to the hot absolute temperature, which is 1 minus 300 over 600, giving 0.5 or 50 per cent. The temperatures must be in kelvin for this to work; using degrees Celsius gives nonsense. No real engine between the same two reservoirs can beat this figure.