A Carnot engine having an efficiency of is being used as a refrigerator. If the work done on the refrigerator is 10J, the amount of heat absorbed from the reservoir at lower temperature is :

Engineering

Physics

Heat engine Refrigerator Entropy

Question

A Carnot engine having an efficiency of $\frac{1}{10}$ is being used as a refrigerator. If the work done on the refrigerator is 10J, the amount of heat absorbed from the reservoir at lower temperature is :

99 J

90 J

1 J

100 J

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For Carnot engine using as refrigerator

$W = Q_{2} (\frac{T_{1}}{T_{2}} - 1)$

$It is given η = \frac{1}{10} \Rightarrow η = 1 - \frac{T_{2}}{T_{1}} \Rightarrow \frac{T_{2}}{T_{1}} = \frac{9}{10}$

So, Q₂ = 90 J (as W = 10 J)