Two identical light bulbs are connected in series and hooked up to a 110 V constant voltage source. The current through each bulb is 0.25 A. Find the resistance of a single light bulb.

Answer 1

Using the equation V=IR, since we have V and I, we get R=440Ω. Since that is the equivalent resistance of both lightbulbs, we need to find the individual value from it. We know that the lightbulbs are identical and are in series, and we know that resistance adds in series, so the two lightbulbs should share this equivalent value equally. Thus, an individual lightbulb has a resistance of 220Ω.