Kinetic Theory Of Gases Question 10

Question: A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by $ 62{}^\circ C $ , the efficiency of the engine is doubled. The temperatures of the source and sink are

Options:

A) $ 80{}^\circ C $ , $ 37{}^\circ C $

B) $ 95{}^\circ C $ , $ 98{}^\circ C $

C) $ 90{}^\circ C $ , $ 37{}^\circ C $

D) $ 99{}^\circ C $ , $ 37{}^\circ C $

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Answer:

Correct Answer: D

Solution:

[d] Initially $ \eta =( 1-\frac{T _{2}}{T _{1}} )=\frac{W}{Q}=\frac{1}{6} $ …(i)

Finally $ \eta =( 1-\frac{T’_2}{T_1})$

=$( 1-\frac{(T _{2}-62)}{T _{1}} )=1-\frac{T _{2}}{T _{1}}+\frac{62}{T _{1}} $

$ =\eta +\frac{62}{T _{1}} $ …(ii)

It is given that $ \eta ‘=2\eta $ hence solving equation (i) and (ii) $ T _{1}=372K=99{}^\circ C $ and $ T _{2}=310K=37{}^\circ C $