A simple circuit contains a battery rated at 12V, connected in series to a filament lamp with a resistance of 3 ohms. What current flows through the filament lamp?

V=IR, where V is voltage (volts), I is current (amps) and R is resistance (ohms). Since V and R are known, I needs to be found. Rearranging the equation gives: I=V/R. Inputting the values gives I=12/3. I=4A