One of my homework questions is giving me trouble: "In, the US, the rms voltage from power outlets (known as line voltage) is 120 V. In the United Kingdom, line voltage is 230 V. If you take a lamp with a standard 100 W incandescent light bulb from the US, how much power will it dissipate if used in the UK? Assume that the electrical resistance of the bulb is constant." So, I know that V=IR and P=VI. V1=120 V and V2= 230 V and the P of the light bulb= 100 W. Should I plug in power of the light bulb to the formula P=IV and find the current and then use that to find the excess power. For example, P/V=I (100W)/(120V)=I I=0.8A P=(0.8A)(230 V)= 200 W - 100 W = 100 W dissipated I have no idea if I am on the right track or not, please help. Thanks in advance.