Thermodynamics Question 328
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) is.
Options:
A) $ 320{}^\circ C $
B) $ 39{}^\circ C $
C) 325 K
D) $ 325{}^\circ C $
Show Answer
Answer:
Correct Answer: B
Solution:
[b]Given $ \beta =5 $
We have, $ \beta =\frac{T _{2}}{T _{1}-T _{2}} $
where $ T _{1}= $ temp. of surrounding,
$ T _{2}= $ temp. of cold body
$ =-13^{0}C=(-13+273)K=260K $
or $ 5=\frac{260}{T _{1}-260} $
$ 5T _{1}=260+1300 $ or $ T _{1}=312K=39^{o}C $ .
