given two lightbulbs w/ the following ratings: 150 W, 120 VAC and 75.0 W, 120 VAC.?

Question

they are connected in series across a potential difference of 120 VAC. assuming what you have learned about DC circuits applies, and that the operating resistances of the bulbs are not affected by the series connection, calculate: (a) the power produced in each bulb, and (b) the total power porduced in the series circuit.

Answer 1

1st bulb resistance is 120*120 / 150 = 96 ohms
2nd bulb 120*120/ 75 = 192 ohms
total resistance is 192+96 = 288

current for bulbs in series is 120/288 = 0.4167
Power in first bulb is 0.4167*0.4167*96 = 17 watts
Power in second bulb is 0.4167*0.4167 * 288 = 50 watts
Total power is 67 watts