Question

The temperature inside a refrigerator is $t_2^{o}C$ and the room temperature is $t_1^{o}C$. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be

• A. $\frac{t_1+t_2}{t_1+273}$
• B. $\frac{t_1}{t_1-t_2}$
• C. $\frac{t_1+273}{t_1-t_2}$
• D. $\frac{t_2+273}{t_1-t_2}$

Answer 1

Answer: (C)

The correct option is C $\frac{t_1+273}{t_1-t_2}$
Heat delivered $=Q_1$

Coefficient of performance $=\beta =\frac{Q_2}{W}=\frac{Q_1-W}{W}=\frac{Q_1}{W}-1=\frac{T_2}{T_1-T_2}$

$\Rightarrow \frac{Q_1}{W}=1+\frac{t_2+273}{t_1-t_2}=\frac{t_1+273}{t_1-t_2}$