A scientist says that the efficiency of his heat engine which work at source temperature 127oC and sink temperature 27oC is 26%, then (a) it is impossible (b) it is possible but less probable (c) it is quite probable (d) data are incomplete.

Answer: (a). Maximum (Carnot) efficiency: ηmax = 1 - (300)/(400) = 0.25 = 25% No engine between these temperatures can exceed 25%; the claimed 26% is larger. So the answer is (a) it is impossible.

A scientist says that the efficiency of his heat engine which work at… | NEET 2001 (AIPMT)

Q92NEET 2001 · AIPMTEasy

Heat Engines, Refrigerators & Second Law

A scientist says that the efficiency of his heat engine which work at source temperature 127oC and sink temperature 27oC is 26%, then

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Answer: (a)

Maximum (Carnot) efficiency: $\eta_{max} = 1 - \frac{300}{400} = 0.25 = 25\%$
No engine between these temperatures can exceed $25\%$ ; the claimed $26\%$ is larger.
So the answer is (a) it is impossible.

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Heat Engines, Refrigerators & Second Law question from NEET 2001 (AIPMT)

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