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Solar Garden Light - Halogen Light Bulbs

Halogen Light Bulb © 2008

In order to understand the halogen light bulb, it is necessary to understand the ordinary incadescent light bulb first. The heart of both the incadescent and halogen light bulb is a tungsten filament, which is surrounded by a glass envelope. This envelope is filled with either argon or nitrogen. An electric current is applied to the tungsten filament which responds by becoming hot, around 4500 degrees. At this temperature, the metal glows intensely, emitting a lot of light in the process.

At this temperature, the tungsten in the filament evaporates and is transported to the glass enclosure. The filament becomes weaker over time, finally breaking, or burning out. Halogen light bulbs are different. They also use a tungstone filament. But the envelope surrounding the filament is made of quartz instead of glass. The quartz, because its melting point is much higher than glass, can be much closer to the filament than glass can.

The glass element is then filled with one of the gasses from the halogen group of elements. These gasses are fluorine, chlorine, bromine, iodine or astatine. The gasses in this group differ from nitrogen and argon in that they will combine with the tungsten as it evaporates and redeposit it on the filament.

The halogen light bulb will last much longer than an incadescent bulb because of the recycling properties of the halogen gasses within it. They burn hotter, though, and emit more light. Halogen light bulbs are used in solar garden lights which must throw more light than an LED. Flood and spot lights are commonly outfitted with halogen bulbs.

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