Answer to Question #307499 in Electric Circuits for Ash

Question

1. Why do lights on a car become dimmer when you start a car?

2. Some Christmas tree lights have a characteristic that when one light (filament) burns out, the lights throughout go

out too. However, burned-out lights go out in other series lights. Discuss the difference between these two sets of

lights.

Answer 1

1. Starter requires a lot of current resulting to high p.d across the starter.

The remaining electrical components including lamps will have lower voltage and hence lower current available.

2. In the first set, the bulbs are in series

In the second set, though the bulb are in series, there is a shunt filament circuit included in every bulb, such that when a bulb burns out, the current passes through the shunt.