Science Questions

Sat, 1st Oct 2005

Part of the show Science of Lasers, Light, Kung Fu and Archimedes

Question

Amy asked:

How does a light bulb work?

Answer

A light bulb is an electrical filament. What you have is a long piece of wire, and when you connect this to a socket, it basically completes a circuit. As electricity passes through, the electrical current excites the metal and gets it hot. As you know, an electric fire glows orange because there's electricity moving through it and it creates heat. In a light bulb, it's set up in such a way that it doesn't just glow red, but it glows white. The key thing about a light bulb is that if you have something that is that hot with oxygen around, just like Dave and Derek's brillo pad, it'll burn. So what they do with a light bulb is that they suck out all of the oxygen and put argon in instead. This is what's called a Nobel gas: it's completely unreactive and inert. It helps the filament to stay the right temperature by getting hot and carrying heat away from the filament to the edge of the glass.

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