Halogen light bulbs work in similar ways as the typical electric bulb does but there are not noticeable differences. Normally, those electric light bulbs you see at home has glass envelope that is thin and frosted. This encloses an inert gas like argon or nitrogen. One would see the burning filament at the center of the lamp or bulb. This is called tungsten. It is a thin metallic wire with a very high melting point, making it ideal to be used in bulbs as it glows at extremely high temperatures that reach 2,500 ° C without melting or getting burnt. The thin filament offers particularly high resistance so when electric current passes by the filament heat build up and the thin wire glows. That is how bulbs glow bright. This process is called incandescence. Another type of electric bulb at home is fluorescent bulb and this one glows in a different fashion but this will not be discussed here.
The matter with ordinary electric bulbs is their low efficiency. Most of them last no more than 1000 hours during typical usage. Electric bulbs convert electrical energy into heat and light, but ordinary bulbs convert much of the electricity to heat. That is why you feel hot near an incandescent lamp because of the heat radiated in all directions. This radiant heat is basically infrared radiation and this is a particularly waste energy. It is like one pays for an electric bulb and gets home with a central heating unit that emits light. This specific inefficiency makes these bulbs not quite practical in the long run. They burn out fast as the tungsten wire filament vaporizes in intense heat. This loss of tungsten causes the filament to run thin within a short time until it burns out and the light bulb gets busted.
There is another kind of incandescent lamp but is more sophisticated and lasts much longer than ordinary ones. These are called halogen light bulbs and they are an exceptional kind of bulb. Like typical incandescent bulbs, they have tungsten filament which burns and glows hot as electricity passes through it. However, unlike the electric bulb in your toilet or garage made of incandescent bulb, the tungsten filament of a halogen lamp is enclosed in a quartz glass and this quartz enclosure locks in a halogen gas. The quartz encloses the filament rather closely, at which distance ordinary glass would get exposed to extreme heat of the glowing filament and melt. The halogen gas that surround the filament has properties that make the tungsten filament last longer. Ordinary electric bulbs use argon or nitrogen and these are relatively non-reactive gases. Has oxygen been used the tungsten would burn out extremely fast.
In the case of halogen bulbs, the presence of a halogen gas allows chemical combination to occur between it and the hot tungsten. The halogen gas atoms (eg iodine or bromine gas) combine with tungsten vapor atoms. In ordinary incandescent bulbs, tungsten vapor atoms are deposited onto the glass surface and this causes darkening of the inner surface of the glass. This does not normally occur in halogen lamps because instead of being deposited onto quartz glass inner surface, the tungsten atoms are captured by the halogen gas atoms and chemically combine with them. Soon, the tungsten atoms are then deposited again onto the tungsten filament. This cycle allows longer life span of the filament.
Halogen bulbs can also burn at much higher temperatures and this means they can even be brighter than non-halogen incandescent lamps. The efficacy and efficiency of halogen bulbs makes them ideal for a larger array of purposes. The quality of light is also better than that of ordinary incandescent lamps.
