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Question 31059
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Kinetic Theory and Thermodynamics: Heat Engine MCQ

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Heat EngineHardQuestion 31059

Question

A steam engine with source at 200°C and sink at 20°C. Its actual efficiency is 25%. Ratio of actual to Carnot efficiency is:
  1. A
    0.6
    Correct
  2. B
    0.7
  3. C
    0.8
  4. D
    0.5

Correct answer

0.6

Explanation

η_Carnot = 1 − 293/473 = 0.38 = 38%. Ratio = 25/38 ≈ 0.66 ≈ 0.7 (closest). Carnot sets upper bound; actual engines have irreversibilities.

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