The filament of an electric bulb glows because of the heating effect of electric current. As the current passes through the bulb it heats the filament which gives off light.
- A filament has lots of opposition or resistance to electricity.
- The filament then heats up and becomes red-hot as a result of this it begins to glow, turning electrical energy into light energy.
- It is because of the Joule effect, which means that as the electrical current flows through them, the resistances heat up.