Question

If a heat engine absorbs 2 KJ heat from a heat source and release 1.5 KJ heat into cold reservoir, then its efficiency is 

(A) 0.5% 

(B) 75% 

(C) 25% 

(D) 50%

Answer 1

Correct option: (C) 25%

Explanation:

Heat absorbed from heat source = 2 KJ = Q₁ 

Heat released = 1.5 KJ = Q₂ 

η = 1 – (Q₂ / Q₁)

= 1 – (1.5 / 2.0)

η = (1/4)

i.e. % efficiency = (1/4) × 100 = 25%