1. The problem statement, all variables and given/known data Q. What will happen when a) A bulb rated 240 V 100W is connected to a 120 V supply . b) A bulb rated 120 V 100W is connected to a 240 V supply 2. Relevant equations P = V2/R 3. The attempt at a solution a) R = 2402/100 = 576Ω Power dissipated when the bulb is put across a 120V supply = 1202/576 = 25W . The bulb lights dimmer . b) R = 1202/100 = 144Ω Power dissipated when the bulb is put across a 240V supply = 2402/144 = 400W . Since power dissipated is more than the rated power ,the bulb fuses . Is this reasoning correct ? Many thanks !