Question

The resistance of an electric heater is 50 Ω when connected to 120 V. How much energy does it use during 15 min of operation?

Answer 1

Answer:

Explanation:

I = V/R = 120 V/ 50 Ω = 2.4 A

P = VI = 120(2.4) = 288 W = 288 J/s

288 J/s (15 min(60s / min)) = 259,200 J

or the electric company would charge for

288 W / (1000 W/kW)•(15/60) hr = 0.072 kW•hr

At $0.20 / kW•hr, that would be under 1½ cents