Calculate the coefficient of performance of a refrigerator working between $-10^{\circ} \mathrm{C}$

Question

Calculate the coefficient of performance of a refrigerator working between $-10^{\circ} \mathrm{C}$ and $20^{\circ} \mathrm{C}$\

Professor PC Thomas Classes · Answer

For a refrigerator $\frac{Q_{2}}{W}$ is called coefficient of performance 
$ \begin{array}{r} \frac{\mathrm{Q}_{2}}{\mathrm{~W}}=\frac{\mathrm{T}_{2}}{\mathrm{~T}_{1}-\mathrm{T}_{2}} \quad \mathrm{~T}_{1}=20^{\circ} \mathrm{C}=\mathrm{K} \ \mathrm{~T}_{2}=-10^{\circ} \mathrm{C}=\mathrm{K} \end{array} $ 
Calculate coefficient of performance\