Question

The efficiency of Carnot’s engine operating between reservoirs, maintained at temperature 27°C and -123°C is ___________

(a) 50%

(b) 24%

(c) 0.75%

(d) 0.4%

I have been asked this question in an international level competition.

My enquiry is from Thermodynamics topic in portion Kinetic Theory of Gases of Engineering Physics I

Answer 1

Right choice is (a) 50%

Easiest explanation: Ƞ=1-T2/T1

Ƞ=1-(273-123)/(273+27)=1-150/300=1/2=50%.