Question

A light bulb, a capacitor and a battery are connected together as shown here, with switch $S$ initially open. When the switch $S$ is closed, which one of the following is true ?

• A. The bulb will light up for an instant when the capacitor starts charging.
• B. The bulb will light up when the capacitor is fully charged.
• C. The bulb will not light up at all.
• D. The bulb will light up and go off at regular intervals.

Answer 1

The correct option is A The bulb will light up for an instant when the capacitor starts charging.

Initially when key is closed, the capacitor acts as short-circuit, so bulb will light up. But finally the capacitor becomes fully charged, so it will act as open circuit, so bulb will not glow.