Question

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.

Answer 1

Resistance of the electric heater, R = 8 Ω
Current I = 15 A

Time, t = 2 hr.

Rate of generation of heat = I² × R

= (15)² × 8

= 255 × 8

= 1800 W

Therefore, heat is produced by the heater at a rate of 1800 W.