The wattage marked on a lightbulb is not an inherent property of the bulb, but depends on the voltage to which it is connected, usually 110 or 120 V. How many amperes flow through a 60-W bulb connected in a 120-V circuit?

Solution 2P Introduction. If I is the current flowing through an instrument having potential difference V , then the power of the instrument is given by P = IV P I = V Step 1 So in the given problem we have P = 60 W V = 120 V Now using the above formula we can write that (60 W) I = (120 V )0.5 A So the current through a 60 W bulb connected to a 120 V supply is 0.5 A.