A carnot engine having an efficiency of eta=1/10 as heat engine is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is _____

A carnot engine having an efficiency of eta=1/10 as heat engine is use

1.	A carnot engine having an efficiency of eta=1/10 as heat engine is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is _____
Answer» 100 J 99 J 90 J 1 J Solution :Coefficient performance of REFRIGERATION, `alpha Q_2/W=Q_2/(Q_1-Q_2)` `therefore Q_2/W=(Q_2/Q_1)/(1-Q_2/Q_1)` `therefore Q_2/W=(1-eta)/eta[eta=1-Q_2/Q_1 RARR Q_2/Q_1=1=eta]` `therefore Q_2=Wxx(1-eta)/eta` `therefore Q_2=10xx(1-1/10)/(1/10)` `therefore Q_2`=90 J