A) \[{{31}^{\text{o}}}C\]
B) \[{{41}^{\text{o}}}C\]
C) \[{{11}^{\text{o}}}C\]
D) \[{{21}^{\text{o}}}C\]
Correct Answer: A
Solution :
Key Concept Coefficient of performance (\[\beta \]) of a refrigerator is defined, as the ratio of quantity of heat removed per cycle (\[{{O}_{2}}\]) to the work done on the working substance per cycle to remove this heat. Given, coefficient of performance of a refrigerator, \[\beta =5\] Temperature of surface i.e. inside freezer, \[{{T}_{2}}={{20}^{{}^\circ }}C=-20+273=253K\] Temperature of surrounding i.e. heat rejected outside \[{{T}_{1}}=?\] So. \[\beta =\frac{{{T}_{2}}}{{{T}_{1}}-{{T}_{2}}}\Rightarrow 5=\frac{253}{{{T}_{1}}-253}\] \[\,\Rightarrow \,\,\,\,\,\,\,5{{T}_{1}}-1266=253\] \[\,\Rightarrow \,\,\,\,\,\,\,5{{T}_{1}}-1518\] \[{{T}_{1}}=\frac{1518}{5}=303.6K\] \[{{T}_{1}}=303.6-273=31{{\,}^{{}^\circ }}C\]
You need to login to perform this action.
You will be redirected in
3 sec
