Final answer:
In a series circuit, the total resistance is the sum of individual resistances. The current flowing in each brake lightbulb connected in series in a car's 12-V electrical system would be approximately 0.909 A.
Step-by-step explanation:
In a series circuit, the total resistance is equal to the sum of the individual resistances. Since the brake lightbulbs are connected in series, their resistances simply add up. In this case, each brake lightbulb has a resistance of 6.6 Ω, so the total resistance would be 2 times 6.6 Ω, which is 13.2 Ω.
Now we can use Ohm's law, which states that I = V/R, to find the current that flows in each bulb. Given that the electrical system in cars is 12 V, we can substitute these values into the formula to find I. Calculating I = 12 V / 13.2 Ω gives us a current of approximately 0.909 A for each bulb.