Question

An electric bulb in a closed circuit is not glowing. Which of the following can be a reason?

• A. Bulb's filament is broken.
• B. Filament of the bulb is made of Tungsten.
• C. Switch in the circuit is on.
• D. Wires are made of copper.

Answer 1

The correct option is A Bulb's filament is broken.

If an electric bulb does not glow even when it is connected to the cell, it could be due to one of the following reasons:

1. The bulb is fused. The part of a bulb that completes the circuit is its filament. A bulb that has a broken filament is termed as a 'fused bulb'.
2. Circuit may be broken. This may be because switch is off, a blown fuse, burnt wires, etc.
3. Connecting wires are made of an insulator. Usually copper, being a good conductor, is used to make connecting wires.

So, the circuit was not complete and hence the bulb did not glow.