Question

A reversible heat engine absorbs 20 kJ of heat from a source at 500 K and dissipates it to the reservoir at 400 K. The efficiency of the heat engine is \(\underline{\hspace{2cm}}\) %.

Hint:

The efficiency of a Carnot engine depends on the temperatures of the heat source and sink. The higher the temperature difference, the higher the efficiency.

Answer 1

Correct Answer: 20

The efficiency of a reversible heat engine (Carnot engine) is given by the formula:
\[ \eta = 1 - \frac{T_C}{T_H} \] where \( T_H \) is the temperature of the heat source and \( T_C \) is the temperature of the heat sink.
Here, \( T_H = 500 \, K \) and \( T_C = 400 \, K \). Substituting the values into the formula:
\[ \eta = 1 - \frac{400}{500} = 1 - 0.8 = 0.2 \] Thus, the efficiency of the heat engine is \( 20% \).