Question

The following is a schematic representation of a refrigerator or a heat pump.

The coefficient of performance $(\alpha)$ of a refrigerator is given by

• A. $\alpha=\frac{Q_{1}}{W}$
• B. $\alpha=\frac{Q_{1}}{Q_{1}-Q_{2}}$
• C. $\alpha=\frac{W}{Q_{1}}$
• D. $\alpha=\frac{Q_{2}}{Q_{1}-Q_{2}}$

Answer 1

Answer: (D)

$\alpha=\frac{Q_{2}}{W}$
Now, $Q_{1}=Q_{2}+W$ or $Q_{2}=Q_{1}-Q_{2}$
$\Rightarrow \alpha=\frac{Q_{2}}{Q_{1}-Q_{2}}$.