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

Work-done (W) = P0V0∵Area under PV graph gives Workdone, W=area of square=2P0 -P0(2V0-V0=P0V0---(1)According to principle of calorimetryHeat given  =nCvdTAB+nCpdTBC=32nR(TB−TA)+52nR(TC−TB)=32(nRTB−nRTA)+52(nRTC−nRTB)=32(2P0V0−P0V0)+52(4P0V0−2P0V0) (∵PV=nRT)=32(P0V0)+52(2P0V0)Q=132P0V0----(2) Thermal efficiency of engine (η) = WQgiven=PoV013PoV02=213=0.15   (From equations (1) and (2))