A Carnot engine having an efficiency of 1/5 as heat engine, is used as a refrigerator. If the work done on the system is 15 J, the amount of energy absorbed from the reservoir at lower temperature is :

60 J

\(\beta\) = \(\frac{1 - \eta }{\eta}\)

\(\eta\) = 1/5 ;

\(\Rightarrow \beta\) = 4 = \(\frac{Q}{W}\) 

\(\Rightarrow \beta\) = 4 = \(\frac{Q}{15}\) 

Q = 60 J