Question

A Carnot engine operates between $227^{\circ }C$ and $27^{\circ }C$. Efficiency of the engine will be :

• A. 1/3
• B. 2/5
• C. 3/4
• D. 3/5

Answer 1

Answer: (B)

Efficiency of heat engine is the fraction of the total heat supplied to the engine
which is converted into work that is
$\eta =1-\frac{Q_2}{Q_1}$
$=1-\frac{T_2}{T_1}$
$\Rightarrow \eta =\frac{T_1-T_2}{T_1}$
Given, $T_1=227^{\circ }C$
$=227+273=500K$
$T_2=27^{\circ }C$
$=273+27=300K$
$\therefore \eta =\frac{500-300}{500}$
$=\frac{200}{500}=\frac{2}{5}$