For which combination of working temperatures, the efficiency of engine is the least ?
100 K, 80 K
40 K, 20 K
80 K, 60 K
60 K, 40 K
A Carnot's engine is made to work between 200°C and 0°C first and then between 0°C and − 200°C. The ratio of efficiencies of the engine in the two cases is
1 : 1.73
1.73 : 1
1 : 2
1 : 1
A.
1 : 1.73
T1 = 200 + 273 = 473°K
T2 = 0 + 273 = 273°K
For second,
T1 = 0 + 273 = 273°K
T2 = − 200 + 273 = 73°K