A halogen bulb, more commonly referred to as a quartz-halogen lamp or a tungsten-halogen lamp, is a type of light bulb used in lamps and other lighting fixtures.
How Halogens Work
The mechanism behind a halogen lamp is similar to that of an incandescent light bulb. A light bulb consists of a tungsten filament and a glass envelope that encloses a gas, typically argon that surrounds the filament. A halogen bulb uses a tungsten filament similar to a conventional incandescent light bulb, but the tubular-shaped envelope surrounding the filament is made of quartz as opposed to glass. Quartz is used because the envelope is much closer to the filament and would melt if it were made of glass because of the heat emitted from the filament.
Another difference is that a type of halogen gas, which may include fluoride, chlorine, bromine, iodine, and astatine, is used instead of argon. The halogen gas, typically bromine or iodine, combines chemically with the tungsten vapors to allow the filament to last much longer than a conventional incandescent light bulb. Because of this reaction, halogen light bulbs are much hotter than regular light bulbs.
Halogen Advantages and Disadvantages
Halogen light bulbs are more expensive to purchase than regular light bulbs however, they last much longer than regular light bulbs-about twice as long, or as many as 2000 hours. Thus, they are more efficient. That said however, they are not as energy efficient as fluorescent lighting though because most of the electricity used to provide the light is wasted as heat instead of being used to provide light. Halogen lamps also have the disadvantage of posing the threat of fire or burns because they burn so hotly, up to 1100 degrees Fahrenheit.
Where To Use Halogens
Halogen lights are used for applications such as car headlights or where direct and very precise light is required. Halogen lamps provide a very white light and should be used primarily for down lighting. In other words they provide light from above directly onto a specific point, rather than illuminating a room.
In recent years, halogen lights have become a popular choice for torchiere floor lamps, which direct light upward onto the ceiling. As a result, these types of floor lamps are less energy efficient. While halogen lamps may be a good choice for a ceiling mounted chandelier light fixture, they are not a good choice for table or floor lamps.