When you turn on a lamp, electricity makes the bulb light up. How?
The electricity flows through a wire into the bulb. It travels around a wire inside the bulb. Then it leaves the bulb. Part of the electricity’s path through the bulb is a filament, a very thin thread of coiled wire. The filament is so thin that electrons have to push hard to get through.
The push of the electrons makes the molecules in the filament move faster. As the molecules speed up, they get so hot that their electrons give off energy. Then the filament glows.
The filament in the light bulb is made of metal called tungsten. A tungsten wire can get very hot without burning or melting. But as tungsten is heated, its molecules very slowly change to a gas and leave the wire. So, as the light bulb glows, the filament gets thinner and thinner.
After many hours of use, the filament breaks. The bulb is “burned out”. The electricity can’t get across the break in the filament. Then you put in a new bulb. Now the electric current has a path to follow. The lamp lights up again.
Picture Credit : Google
