Question

A carnot engine exhausting heat at ${77}^{\circ }$C is working on $30$% efficiency then it must take heat from :

• A. ${673}^{\circ }C$
• B. ${327}^{\circ }C$
• C. ${227}^{\circ }C$
• D. ${127}^{\circ }C$

Answer 1

The correct option is C ${227}^{\circ }C$

$\frac{T_H-T_L}{T_H}=0.3$
$T_H-350=T_{H}0.3$
$\Rightarrow 0.7T_H=350$ $\Rightarrow T_H=500K={227}^{\circ }C$