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⚛️ Physics  ·  Thermodynamics  ·  NEET & JEE

A Carnot engine absorbs 600 J at 400 K and rejects heat to a sink at 300 K. The work it does per cycle is:

Answer: 150 J.

  • A 600 J
  • B 450 J
  • C 300 J
  • D 150 J

Correct answer: D. 150 J

Explanation: η = 1 - 300/400 = 0.25, so W = 0.25 × 600 = 150 J.

Carnot Cycle (P-V Diagram)VP1→2: isothermal expansion (T_H)2→3: adiabatic expansion3→4: isothermal compression (T_C)4→1: adiabatic compression1234Net work done by the gas = area enclosed by the loop 1→2→3→4→1

The Carnot cycle alternates two isothermal steps (heat absorbed at TH, released at TC) with two adiabatic steps (no heat exchange); the enclosed loop area equals the net work output, and η = 1−TC/TH is the maximum possible efficiency between those two temperatures.

Concept context

Laws of thermodynamics, heat engines, entropy, and gas processes.

Read the full Thermodynamics notes →