- Electrical filament
An electrical filament is a thread of
metal, usually tungsten, which is used to convert electricityinto light in incandescent light bulbs (as developed in 1874by Alexander Lodyginand in 1878by Joseph Wilson Swan, among others), and into heat in vacuum tubedevices.
The first successful light bulb filaments were made of
carbon(from bamboo), later replaced with tungsten.
electrical currenttravels through the filament and because of the electrical resistanceof the filament makes it white-hot and generates light and heat. It is normally in a vacuumor a noble gasor inert gasinside a glassenclosure to stop oxidation. Small amounts of a halogencan be added to facilitate transport of evaporated tungstenatoms back to the filament, resulting in significantly prolonged lifetime when used at higher temperatures, which is exploited in halogen lamps.Electrical filaments are used in hot cathodes of various types of vacuum tubes and electron guns as sources of electrons.
Types of filament
There are several different types of filament configuration available and it all depends on the lamp itself, and what characteristics are required. Some of these include but are not limited to C-6, CC-6, C-2V, CC-2V, C-8, CC-88, C-2F, CC-2F, C-Bar, C-Bar-6, C-8I, C-2R, CC-2R, Axial.
* [http://filament.bravehost.com/light.htm An brief article explaing the light bulb - "The Composition of the Light Bulb"]
* [http://inventors.about.com/library/inventors/bllight.htm The history of the light bulb]
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