Automotive Electronics Practice Test

What happens to the current flow if one taillight bulb in a parallel circuit burns out?

1. The current flow increases and the other bulbs get brighter

2. The current flow decreases because only three bulbs are operating

3. The current remains the same because all the bulbs are wired in parallel

4. The current drops to zero and the other bulbs go out

The correct answer is: The current flow decreases because only three bulbs are operating

In a parallel circuit, each component is connected across the same voltage source, meaning that each bulb receives the full voltage supplied. When one taillight bulb burns out in a parallel circuit, it essentially becomes an open circuit at that particular point, which means that the current flowing through that branch drops to zero. However, the other bulbs remain functional because they still have their own pathways to the power source. The overall current flowing from the power source does change in the sense that it decreases, because there is now one less path for the current to take. The other bulbs will continue to operate normally, but the total current supplied by the source will be lower due to the loss of the burned-out bulb. The correct answer reflects this understanding that while the remaining bulbs still light up, the total current flowing through the circuit decreases because one of the paths is no longer conducting; thus, it correctly identifies the effect of the burnt-out bulb in the parallel configuration.