Question

When you switch on an electric bulb, it glows. Can you tell what makes it glow?

• A. the glass case of the bulb
• B. the thin filament
• C. the thick wires supporting the filament
• D. gases inside the glass case of the bulb

Answer 1

The correct option is B

the thin filament

The incandescent light bulb consists of a glass enclosure which is either vacuum or is filled with a low-pressure noble gas. Inside this is a filament, often made of tungsten, and through which an electrical current is passed. The heating of the filament causes it to emit light and the vacuum/inert gas inside the bulb prevents the filament from burning out. A bulb uses heat caused by an electrical current. When electrical current passes through a wire, it causes the wire to heat. The wire, or filament, gets so hot that it glows and gives off light energy.