Electric light bulbs that use a filament were invented at the same time late in the 19th century by Swan in England and Edison in America. These bulbs give out light as electricity flows through a special thin wire called a filament. This wire does not easily let electricity pass through it, so as a current flows it gets so hot it eventually gives out light.

These kinds of bulb are called incandescent bulbs because burning to give out light is called incandescence.

We still use these kinds of bulb, although many have been phased out because they give out – and waste – a lot of electricity as well as giving light. You now find a more efficient version of them as halogen lamps in desktop lamps and in the kinds of light that are placed in the ceilings of rooms.

Another way of giving out light is to make a special material called a phosphor glow. That is how fluorescent bulbs work. Because fluorescent bulbs do not get hot, much more of the electricity is used making light than heat. That is why they are called energy friendly bulbs, eco bulbs and similar words.

It is important to note that fluorescent bulbs give out a different kind of light to incandescent bulbs and many people do not find them comfortable to use for reading.