JEE Main2017PhysicsThermodynamicsActual
An engine operates by taking n moles of an ideal gas through the cycle A B C D A shown in figure. The thermal efficiency of the engine is: (Take C v = 1.5 R , where R is gas constant)
Options
- A0 . 24
- B0 . 15
- C0 . 32
- D0 . 08
Correct answer
B. 0 . 15
Step-by-step solution
Work done in cycle = area under closed curve W = P 0 V 0 Heat given = Q A B + Q B C = n C V   Δ T A B + n C p   Δ T B C = 3 2 n R T B - n R T A + 5 2 n R T C - n R T B = 3 2 2 P 0 V 0 - P 0 V 0 + 5 2 4 P 0 V 0 - 2 P 0 V = 13 2   P 0 V 0 Thermal efficiency, η = W Q a b s o r b e d = 2 13 = 0.15