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JEE Main 2022 (24 Jun, Shift 1) · Heat Engines, Refrigerators & Second Law

Heat Engines, Refrigerators & Second Law question from JEE Main 2022 (24 Jun, Shift 1)

Q36JEE Main 2022 · 24 JUN · SHIFT 1Medium

Heat Engines, Refrigerators & Second Law

A Carnot engine whose heat sink is at 27 $^\circ$ C, has an efficiency of 25%. By how many degrees should the temperature of the source be changed to increase the efficiency by 100% of the original efficiency?

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Answer: (b)

$T_2 = 300\text{ K}$ : $T_1 = \frac{300}{1 - 0.25} = 400\text{ K}$ .
Efficiency doubles to 0.5: $T_1' = \frac{300}{0.5} = 600\text{ K}$ .
Change $= 600 - 400 = 200\text{ K} = 200^\circ\text{C}$
So the answer is (b) increases by $200^\circ\text{C}$ .

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