Light is produced by incandescence when light comes from a heated solid. We see an example of incandescence when an iron bar is heated to a very high temperature. As the temperature rises it glows--red at first and then white. The process we are seeing which turns heat energy into light energy is called incandescence.

Incandescent lamps derive their name from this process. In these lamps the filament is made of tungsten --a special metal which can stay at a high temperature for a hundreds of hours without burning through.

                    Incandescent Filament

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