Question

The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is $-{20}^{\circ }C$, the temperature of the surroundings to which it rejects heat is:

• A. ${11}^{\circ }C$
  
• B. ${21}^{\circ }C$
  
• C. ${31}^{\circ }C$
  
• D. ${41}^{\circ }C$

Answer 1

The correct option is C ${31}^{\circ }C$.

Given,
Coefficient of performance
$\beta =5$
$T_L=273-20=253K$

We know that,
$\beta =\frac{T_L}{T_H-T_L}=\frac{256}{T_H-253}$
$T_H=303.6K$
$T_H={30.6}^{\circ }={31}^{\circ }C$.