1. The problem statement, all variables and given/known data Two 1.80 V batteries—with their positive terminals in the same direction—are inserted in series into the barrel of a flashlight. One battery has an internal resistance of R1 = 0.280Ω, the other an internal resistance of R2 = 0.155Ω. When the switch is closed, a current of 0.600 A passes through the lamp. 2. Relevant equations R = V/I resistance = electric potential / current 3. The attempt at a solution Underlined in black is the data I was given, as you can see in the question. I drew two batteries and a lightbulb connected in series. I multiplied 0.6 amps times resistance for each battery, and found the electric potential in volts for each battery. Knowing only the current in the lightbulb, but not the electric potential or the resistance, how am I supposed to solve this problem? I only have current in the lightbulb and resistance in the batteries, and I don't know how to use that to determine resistance in the lightbulb. Thanks.