Question

In a Carnot engine, the absolute temperature of the source is 25% more than the absolute temperature of the sink. The efficiency of the engine is

• A. 10%
• B. 50%
• C. 25%
• D. 20%

Hint:

For Carnot engines, always express the temperature ratio correctly when given percentage increases.

Answer 1

The Correct Option is D

The efficiency of a Carnot engine is given by: \[ \eta = 1 - \frac{T_C}{T_H} \] Given that \( T_H = 1.25 T_C \), we substitute: \[ \eta = 1 - \frac{T_C}{1.25T_C} \] \[ = 1 - \frac{1}{1.25} = 1 - 0.8 = 0.2 \] \[ = 20\% \] Thus, the efficiency of the engine is 20\%.