Student Login

Home›Chapters›Thermodynamics PYQs›Heat Engines, Refrigerators & Second Law›Question 65

JEE Main 2017 (8 Apr, Shift 1) · Heat Engines, Refrigerators & Second Law

Heat Engines, Refrigerators & Second Law question from JEE Main 2017 (8 Apr, Shift 1)

Q65JEE Main 2017 · 8 APR · SHIFT 1Difficult

Heat Engines, Refrigerators & Second Law

An engine operates by taking n moles of an ideal gas through the cycle ABCDA shown in figure. The thermal efficiency of the engine is: (Take Cv = 1.5 R, where R is gas constant)

Show answer and solution

Answer: (b)

Net work = area of rectangle $= (2P_0 - P_0)(2V_0 - V_0) = P_0V_0$ .
Heat in A→B (isochoric): $nC_V\Delta T = 1.5(2P_0V_0 - P_0V_0) = 1.5P_0V_0$
Heat in B→C (isobaric, $C_P = 2.5R$ ): $2.5 \times 2P_0(2V_0 - V_0) = 5P_0V_0$
$\eta = \frac{P_0V_0}{6.5P_0V_0} \approx 0.15$
So the answer is (b) 0.15.

Report a mistake

More questions on Heat Engines, Refrigerators & Second Law

The temperature inside a refrigerator is t2 oC and the room temperature is t1 oC. The…NEET 2016 (Phase 2)
A refrigerator works between 4oC and 30oC. It is required to remove 600 calories of heat…NEET 2016 (Phase 1)
A Carnot freezer takes heat from water at 0oC inside it and rejects it to the room at a…JEE Main 2016 (10 Apr, Shift 1)
The coefficient of performance of a refrigerator is 5. If the temperature inside freezer…NEET 2015 (AIPMT)
A Carnot engine, having an efficiency of η = 1/10 as heat engine, is used as a…NEET 2015 (AIPMT, Cancelled Paper)
A solid body of constant heat capacity 1 J/° C is being heated by keeping it in contact…JEE Main 2015
A Carnot engine absorbs 1000 J of heat energy from a reservoir at 127oC and rejects 600 J…JEE Main 2014 (12 Apr, Shift 1)
Two Carnot engines A and B are operated in series. The engine A receives heat from the…NEET 2013