Question

The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is

• A. 26.8%
• B. 6.25%
• C. 20%
• D. 12.5%

Answer 1

The Correct Option is A

To determine the efficiency of an ideal heat engine working between the freezing point and boiling point of water, we use the Carnot efficiency formula:

\( \eta = \left(1 - \frac{T_C}{T_H}\right) \times 100\% \)

where:

• \( T_H \) is the absolute temperature of the hot reservoir (boiling point of water).
• \( T_C \) is the absolute temperature of the cold reservoir (freezing point of water).

In this case:

• \( T_H = 100^\circ\text{C} = 373\,\text{K} \)
• \( T_C = 0^\circ\text{C} = 273\,\text{K} \)

Substituting the values:

\( \eta = \left(1 - \frac{273}{373}\right) \times 100\% \)

\( \eta = \left(1 - 0.732\right) \times 100\% \)

\( \eta = 0.268 \times 100\% = 26.8\% \)

Thus, the efficiency is 26.8%.