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Theatre Production Join us Nov. Show Search Bar:. I have heard a light bulb has glass around it to keep air away from the filament.
Can a light bulb burn in space where there is no air without glass around it? August We may have all heard of interesting things happening in space where there is a weightless environment not gravity free or where there is no air. The Jackson Sun chose to discontinue monthly articles in and now they only appear as requested. Unfortunately, this isn't very efficient. Most of the energy that goes into an incandescent bulb is lost as heat.
In fact, a typical light bulb produces perhaps 15 lumens per watt of input power compared to a fluorescent bulb, which produces between 50 and lumens per watt. Combustion offers another way to produce photons. Combustion occurs when a substance -- the fuel -- combines rapidly with oxygen, producing heat and light.
If you study a campfire or even a candle flame carefully, you will notice a small colorless gap between the wood or the wick and the flames. In this gap, gases are rising and getting heated. When they finally get hot enough, the gases combine with oxygen and are able to emit light. The flame, then, is nothing more than a mixture of reacting gases emitting visible, infrared and some ultraviolet light. Sign up for our Newsletter!
On Earth , combustion is usually a reaction between oxygen in the atmosphere and some heated material, but other combinations of chemicals will combust as well. The filament in a light bulb is housed in a sealed, oxygen-free chamber to prevent combustion. In the first light bulbs, all the air was sucked out of the bulb to create a near vacuum -- an area with no matter in it.
Since there wasn't any gaseous matter present or hardly any , the material could not combust. The problem with this approach was the evaporation of the tungsten atoms. At such extreme temperatures, the occasional tungsten atom vibrates enough to detach from the atoms around it and flies into the air.
In a vacuum bulb, free tungsten atoms shoot out in a straight line and collect on the inside of the glass. As more and more atoms evaporate, the filament starts to disintegrate, and the glass starts to get darker.
This reduces the life of the bulb considerably. In a modern light bulb, inert gases , typically argon, greatly reduce this loss of tungsten. When a tungsten atom evaporates, chances are it will collide with an argon atom and bounce right back toward the filament, where it will rejoin the solid structure.
Since inert gases normally don't react with other elements, there is no chance of the elements combining in a combustion reaction. Cheap, effective and easy-to-use, the light bulb has proved a monstrous success. It is still the most popular method of bringing light indoors and extending the day after sundown.
But by all indications, it will eventually give way to more advanced technologies, because it isn't very efficient. Incandescent light bulbs give off most of their energy in the form of heat-carrying infrared light photons -- only about 10 percent of the light produced is in the visible spectrum.
This wastes a lot of electricity. Cool light sources , such as fluorescent lamps and LEDs , don't waste a lot of energy generating heat -- they give off mostly visible light. For this reason, they are slowly edging out the old reliable light bulb.
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