Question

Carnot engine cannot give $100\%$ efficiency, because we cannot:

• A. eleminate friction
• B. find ideal sources
• C. prevent radiation
• D. reach absolute zero temperature

Answer 1

Answer: (D)

The efficiency of Carnot engine is
$\eta =\frac{T_1-T_2}{T_1}=1-\frac{T_2}{T_1}\dots$(1)
The value of efficiency of Carnot engine can be $1$ or $100\%$, if the sink temperature $\left(T_2\right)$ must be $0K$. As practically absolute zero temperature can not be achieved hence, Carnot engine can not give $100\%$ efficiency.