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How does a light bulb work?

 

An incandescent light-bulb takes just enough electric current to make a piece of metal glow brightly enough to give out visible light yet not get so hot that it melts and breaks. The piece of metal is called a tungsten filament.

Experiments were made with different materials to use as the filament, including natural fibres, pure metals and alloys of different metals, to find the material which had the longest life whilst glowing brightly enough to give out visible light. The metal Tungsten was found to be the best.

Also experiments were made trying a vacuum or different kinds of gas inside the glass bulb to find out which was the best. For many years Nitrogen gas was found to be the best but other gases or mixtures of gases may now be used. Fluorescent light bulbs electrically charge a gas (sometimes one of the inert gases like neon).

Whilst it is normal every-day talk to say that a light bulb or a lamp is "burning", that is not strictly accurate because, speaking strictly scientifically, the word "burning" has a very precise meaning. When something is said to be "burning" it means the material is combining with the element Oxygen to form a compound called an Oxide.

For example when Carbon is burnt it makes either Carbon Monoxide or Carbon Dioxide or a mixture of those two gases. How much of each is made depends on the actual conditions in which the Carbon is being burnt. That is why it is scientifically correct to say that a light bulb is "glowing" and not that it is "burning".

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