Two 200 W (120 V) lightbulbs are wired in series, then the combination is connected to a 120 V supply. How much power is dissipated by each bulb?

Answer 1

All calculations are done with the assumption that the resistance of the light bulbs remain constant.

P = E^2/R.
200 = 120^2/R,
R = 72 Ohms.

P = 60^2/72 = 50 Watts = Power dissipated by each bulb.