Thermodynamics Question 168
Question: An ideal refrigerator has a freezer at a temperature of $ -13{}^\circ C. $ The coefficient of performance of the engine is 5. The temperature of the air (to which heat is rejected) will be
[BHU 2000; CPMT 2002]
Options:
A) 325°C
B) 325K
C) 39°C
D) 320°C
Show Answer
Answer:
Correct Answer: C
Solution:
Coefficient of performance $ K=\frac{T _{2}}{T _{1}-T _{2}} $
Therefore $ 5=\frac{(273-13)}{T _{1}-(273-13)}=\frac{260}{T _{1}-260} $
Therefore $ 5T _{1}-1300=260 $
Therefore $ 5T _{1}=1560 $
Therefore $ T _{1}=312K\to 39{}^\circ C $
