Question

The maximum efficiency of a heat engine operating between ${100}^{\circ }C$ and ${25}^{\circ }C$ is:

• A. 20%
• B. 22.2%
• C. 25%
• D. None of the above

Answer 1

Answer: (A)

20%

Maximum efficiency is for engines.

For engines, we have

$T_1=25+273=298K$

$T_2=100+273=373K$

$\eta =\frac{T_2-T_1}{T_2}$

$\eta =\frac{373-298}{373}=\left[\frac{75}{373}\right]$

$\eta =0.20$

Hence, $20\%$.

So, option $A$ is correct.