JEE Main202124 Feb 2021Morning ShiftPhysicsThermodynamicsActual
n mole of a perfect gas undergoes a cyclic process A B C A (see figure) consisting of the following processes. A → B : Isothermal expansion at temperature T so that the volume is doubled from V 1 to V 2 = 2 V 1 and pressure changes from P 1 to P 2 B → C : Isobaric compression at pressure P 2 to initial volume V 1 . C → A : Isochoric change leading to change of pressure from P 2 to P 1 Total work don
Options
- An R T ln 2 - 1 2
- Bn R T ln 2
- Cn R T ln 2 + 1 2
- D0
Correct answer
A. n R T ln 2 - 1 2
Step-by-step solution
W isothermal = nRT ln V 2 V 1 W isobaric = P Δ V = n R Δ T W isochoric = 0 W 1 = n R T ln 2   V   V = n R T ln 2 W 2 = n R T 2 - T = - n R T 2 W 3 = 0 ⇒ W net = W 1 + W 2 + W 3 W net = n R T ln 2 - 1 2