Question

An ideal refrigerator has a freezer at a temperature of $-13 \, ^{o}C$ . The coefficient of performance of the engine is $5$ . The temperature of the air at which heat is rejected will be

• A. $325 \, ^{o}C$
• B. $325 \, K$
• C. $39^{ o}C$
• D. $320^{o}C$

Answer 1

Answer: (C)

Coefficient of performance $\alpha =\frac{T_{C}}{T_{H} - T_{C}}$
$T_{C}=273-13=260K$
$5=\frac{260}{T_{H} - 260}$
$T_{H}=312K$
$\therefore \, \, T_{H}=312-273=39^{o}C$