Incandescent
Incandescent flashlights use incandescent light bulbs which consists of a glass bulb and a tungsten filament. The bulbs are under vacuum or filled with argon, krypton or xenon. Some high-power incandescent flashlight use a halogen lamp where the bulb contains trace of halogen such as iodine or bromine to improve the life and efficacy of the bulb. In all but disposable or novelty flashlights, the bulb is user-replaceable; the bulb life may be only a few hours.
The light output of an incandescent lamp in a flashlight varies widely depending on the type of lamp. A miniature keychain lamp produces one or two lumens. A two D-cell flashlight using a common prefocus-style miniature lamp will produce on the order of 15 to 20 lumens of light and a beam of about 200 candlepower. One popular make of rechargeable focusing flashlight uses a halogen lamp and produces 218 lumens. By comparison, a 60-watt household incandescent lamp will produce about 900 lumens. The luminous efficacy or lumens produced per watt of input of flashlight bulbs varies over the approximate range of 8 to 22 lumens/watt, depending on the size of the bulb and the fill gas, with halogen-filled 12 volt lamps having the highest efficacy.
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Famous quotes containing the word incandescent:
“I waited alone, in the company of orchids, roses and violets who—like people waiting beside you, but to whom you are unknown—maintained a silence which their individuality of living things rendered more imposing and in their chilly manner received the heat from an incandescent coal fire, preciously placed behind a crystal glass, in a white marble tub where it dropped, from time to time, its dangerous rubies.”
—Marcel Proust (1871–1922)
“Don’t think of yourself as an intestinal tract and tangle of nerves in the skull, that will not work unless you drink coffee. Think of yourself as incandescent power, illuminated perhaps and forever talked to by God and his messengers.... Think if Tiffany’s made a mosquito, how wonderful we would think it was!”
—Brenda Ueland (1891–1985)