lightbulb

[naz]

how does a lightbulb work?

[Mattk]

a current passes thru the element,it glows white hot creating the light.

[Calvesy]

The reason the filament is in a glass bulb is so that it can be protected from the cooling and corrosive effects of the air. The bulb normally contains a vacuum or low pressure inert gas. This way the metal can glow white-hot without burning, at least for a thousand hours of use.

[Tim Baxter]

Just to clarify.  The filament is heated by the electric current passing through it just like an electric fire.  It needs to be brighter than an electric fire so more current is allowed to pass through it making it hotter and brighter.  If the filament were in contact with the air then it would oxidise by combining with the Oxygen in the air.  There are two ways of preventing this, either the filament glows in a vacuum or the bulb is filled with an inert gas such as Argon, Xenon or Krypton.  Both these methods exclude Oxygen so there is no degradation of the filament.  You may have noticed that car headlights and now 12V domestic lights are sold as Krypton or Zenon with special quartz glass which give even more light than traditional glass.

See a man called Joseph Swan in Gooooogle.