Automotive Electronics Practice Test

If two bulbs are connected to a parallel circuit and one burns out, what happens to the remaining bulbs?

1. They will all turn off

2. Only the brightest one stays on

3. The others will remain lit and their brightness will not change

4. They will be dimmer than before

The correct answer is: The others will remain lit and their brightness will not change

In a parallel circuit, each bulb is connected across the same voltage source independently of the others. This means that every bulb receives the same voltage, and if one bulb burns out, it essentially opens up that particular branch in the circuit, while the other branches remain intact and continue to receive power. As a result, the remaining bulbs will continue to operate as if nothing has happened. Their brightness will not change because they are still supplied with the same voltage, ensuring that they maintain consistent illumination. This is a key characteristic of parallel circuits, differentiating them from series circuits, where the failure of one component would affect the entire circuit. Thus, in the scenario described, the other bulbs will remain lit and their brightness will not change, which is why this option is correct.