Question

You want to reduce your energy bills.

A) calculate the power of a lightbulb that transfers 6000 joules every minute.
B) calculate the power of a different lightbulb that has a current of 0.05 amps through it when there is a potential difference of 240 volts across it.
C) both bulbs are equally bright. State and explain which lightbulb you should use.

Answer 1

A) P = W / t = 6000 / 60 = 100 J/s == 100 watts

B) P = I V = .05 * 240 = 12 watts

C) Bulb B) uses much less power