Question

A scientist says that the efficiency of his heat engine which operates at source temperature ${127}^{0}C$ and sink temperature ${27}^{0}C$ is 26%, then

• A. It is impossible
• B. It is possible but least probable
• C. It is quite probable
• D. Data are incomplete

Answer 1

The correct option is A It is impossible

Efficiency of a Carnot's cycle is
$\eta =1-\frac{T_{sink}}{T_{source}}=1-\frac{300}{400}=0.25$
So, with these source and sink temperatures, maximum efficiency is 25%, so 26% is impossible.
Option A.