Question

An electric heater is rated 220 V, 500W. calculate the electrical enegry consumed in 4 hours

Answer 1

power=energy/time=>500=energy/4hrs
therefore, energy=500*4=2000

Answer 2

Hey.

Here is the answer.

As, P = 500W , V = 220 V & t = 4h = 4×3600 s

and energy consumed = P × t = 500×4×3600 J

= 7200000 J

or, 500×4 W h = 2000 W h

or, 2000/1000 kWh =2 kWh or 2 units

Thanks.