Question

How much energy is consumed when a current of 5 amperes flows through the filament (or element) of a heater having resistance of 100 ohms for two hours? Express it in joules.

Answer 1

Given:
I = 5 A
R = 100 Ώ
Power consumed, P= I²R
                               = (5)² 100 watt
                               = 2500 watts=2.5 kW

Energy consumed, E = P x time
                                 = 2.5 x 2
                                 = 5 kWh