Question

A carnot engine is working as a refrigetor between $30^{o}C$ and $0^{o}C$ . The coefficient of performance for the engine is

• A. $16$
• B. $1$
• C. $9$
• D. $4$

Answer 1

Answer: (C)

Assuming $K$ to be the coefficient of performance of the carnot refrigerator and $T_{1}$ , $T_{2}$ to be the source and sink temperatures respectively.
Given , $T_{1}=30+273=303K$
$T_{2}=0+273=273K$
According to the formula
$K=\frac{1}{\frac{T_{1}}{T_{2}} - 1}$
$K=\frac{T_{2}}{T_{1} - T_{2}}=\frac{273}{303 - 273}=\frac{273}{30}=9.1\sim eq9$