Question

A heat engine operates between a cold reservoir at temperature T₂ = 400 K and a hot reservoir at temperature T₁. It takes 300 J of heat from the hot re ervoir and delivers 240 J of heat to the cold reservoir in a cycle. The minimum temperature of the hot reservoir has to be ______ K.

विकल्प

• 200

• 300

• 500

• 600

Answer 1

A heat engine operates between a cold reservoir at temperature T₂ = 400 K and a hot reservoir at temperature T₁. It takes 300 J of heat from the hot re ervoir and delivers 240 J of heat to the cold reservoir in a cycle. The minimum temperature of the hot reservoir has to be 500 K.

Explanation:

Given,

Heat taken, Q₁ = 300 J

Heat deliverd, Q₂ = 240 J

Work done by heat engine, W = Q₁ - Q₂ = 300 - 240 = 60J

Efficiency = `W/Q_"in" = 60/300 = 1 - T_2/T_1`

⇒ `1/5 = 1 - 400/T_1 ⇒ 400/T_1 = 4/5 ⇒ T_1 = 500` K