Tungsten-Halogen Lamps

Tungsten-Halogen Lamps

A halogen or tungsten-halogen lamp is a high-pressure incandescent lamp containing a halogen gas such as iodine or bromine which allows the filament to be operated at a higher temperature than an incandescent lamp, increasing its efficacy. Halogen lamps emit brighter, more intense white light than incandescent lamps, but they are smaller than incandescent lamps with comparable wattage rating. However, the characteristics of the two lamp sizes are similar. Because of the higher color temperatures of halogen lamps (3000 K versus 2800 K), they use quartz rather than glass bulbs. The high-temperature chemical reaction involving tungsten and the halogen gas recycles evaporated particles of tungsten back onto the filament surface. These lamps are used in high-intensity desk and reading lamps, vehicle headlights, spotlights, and flashlights.

Care is needed in handling and using 120-V AC halogen lamps because the high bulb temperatures of an illuminated lamp can cause severe skin burns. Fingerprints on the cold quartz surface of a halogen bulb leave an oily residue that shortens lamp life by causing heat to be distributed unevenly over the surface of the bulb when the lamp is illuminated. Most desk and reading lamps have protective glass lenses over the bulbs to prevent accidental burns when they are illuminated and to prevent fingers from touching them when they are cold.

Halogen lamp light makes neutral surfaces appear yellowish-white. It enhances red, orange, and yellow colors, makes complexions appear ruddy, and dulls blue colors. There are lamp shapes used...