About Halogen Lights

Halogen lamps are popular choices for lighting. They are more efficient and brighter than incandescent bulbs, and less expensive than fluorescent bulbs. Since the advent of halogen lights, they have been used in many different areas, such as automobiles, airplanes and theaters. If you have ever wondered why halogen bulbs are such a popular choice, or what the differences are between halogen bulbs and other bulbs, this article will provide some answers.

Incandescent Bulbs

Incandescent light bulbs have a tungsten filament that is held by a glass post. When connected to a power source, the electricity enters one metal contact, flows through the tungsten filament and exits through the other metal contact. Because the tungsten filament's atoms resist the flow of electricity, the filament heats up and glows. Over time the filament degrades due to a process called "sublimation." Essentially, the filament evaporates and then reforms on the inside of the glass bulb. This darkens the bulb, limiting the amount of light it can emit. Today's incandescent bulbs typically have an inert gas inside them to lessen the effects of sublimation.

Halogen Bulbs

The halogen bulb was invented in 1953 by scientists at General Electric. They found that using a small amount of iodine gas (which is a member of the halogen group of gases) caused the sublimation process to enter a regenerative cycle. Instead of coating the inside of the bulb, the tungsten filament would evaporate, combine with the iodine gas and then redeposit itself back on the original tungsten filament. This is known as the "halogen regenerative cycle."

Comparisons With Other Types of Light Bulbs

Because of the halogen regenerative cycle, the tungsten filaments in halogen bulbs last longer than they do in regular incandescent bulbs. Halogen bulbs are also brighter and more efficient than regular incandescent bulbs. Of course, this means that halogen bulbs are hotter as well. Compared with fluorescent bulbs, halogens are far less expensive and can operate about 10 times longer. But fluorescent bulbs are more energy-efficient and do not emit nearly the same amount of heat as halogen bulbs.

Uses of Halogen Bulbs

Because of their brightness, halogen bulbs are used in any situation where a long-lasting but bright bulb is necessary. For instance, many construction crews rely on halogen lights on stands to illuminate dark rooms. Also, many automotive headlights are halogen lights. Even theater stage lights and aircraft landing lights use halogen bulbs. In homes, halogen desk lamps and reading lamps are popular because of the amount of light they generate and their long lifetimes.

Warning

Halogen bulbs can get very hot. If they come into direct contact with drapery or lamp shades, a fire can start. Some college campuses have banned halogen lamps for this reason. According to the U.S. Consumer Product Safety Commission (CPSC), there have been "189 fires and 11 deaths since 1992 involving halogen torchiere floor lamps." To avoid fires, the CPSC recommends using bulbs that are 300 watts or less, and making sure that draperies or other cloths cannot come into contact with the bulb.

Resources

• CPSC Halogen Lamp Safety Guidelines