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⚛️ Physics  ·  Thermodynamics  ·  NEET & JEE

One mole of an ideal gas (γ = 1.4) is adiabatically compressed to half its volume. The ratio of final to initial temperature is approximately:

Answer: 1.32.

  • A 0.76
  • B 1.32
  • C 1.4
  • D 2

Correct answer: B. 1.32

Explanation: T₂/T₁ = (V₁/V₂)<sup>γ−1</sup> = 2<sup>0.4</sup> ≈ 1.32.

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 →