 Hot-burning "halogen bulbs"
can last two or three times longer than regular bulbs because they
are filled with chemically active halogen gases that preserve the
filament.
The filament of an ordinary light bulb burns out because atoms of
tungsten evaporate from its surface, so
that it becomes thinner and thinner until it breaks. The evaporated
tungsten is deposited on the inside surface of the bulb, where it
forms a dark deposit.
The gas inside a halogen bulb combines with the tungsten atoms
that condense on the glass, removing the deposit. When the combined
molecules touch the hot filament, the
tungsten is redeposited there, and the gas is released to do the
same trick again.
A halogen bulb is often 10 to 20 percent more efficient than an
ordinary incandescent bulb of similar
voltage, wattage, and life expectancy. Halogen bulbs may also have
two to three times as long a lifetime as ordinary bulbs, sometimes
also with an improvement in efficiency of up to 10 percent. |
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note:
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halogen: 卤素
filament: 灯丝
tungsten: 钨
molecule: 分子
incandescent bulb: 白炽灯泡 | |
