An ideal frictionless engine absorbs heat at 400 K and exhausts heat at 300 K.Its efficiency is
A)25%.
B)33%.
C)75%.
D)133%.

Question

Quizplus · Accepted Answer

The efficiency of an ideal heat engine is given by the formula:$$Efficiency = 1 - \frac{T_C}{T_H}$$where $T_C$ is the temperature of the cold reservoir and $T_H$ is the temperature of the hot reservoir.In this case, $T_C = 300 K$ and $T_H = 400 K$, so the efficiency is:$$Efficiency = 1 - \frac{300 K}{400 K} = 0.25 = 25%$$Therefore, the correct answer is A.

An Ideal Frictionless Engine Absorbs Heat at 400 K and Exhausts