Building & Home Articles Garden & Landscaping Articles Light Bulbs
| Light Bulbs |
 |
 |
 |
|
The standard light bulb is very simply structured. On the base, you have two metal contacts, which then connect to the ends of the bulbs electrical circuit. The two metal contacts are attached to two strong wires, and they connect to a thin filament of metal. This filament is located in the middle of the bulb and is held in place by a glass mount. All of this, the wires and the filament, are housed in a glass bulb, which will be filled with an inert gas like argon.
The standard light bulb is very simply structured. On the base, you have two metal contacts, which then connect to the ends of the bulbs electrical circuit. The two metal contacts are attached to two strong wires, and they connect to a thin filament of metal. This filament is located in the middle of the bulb and is held in place by a glass mount. All of this, the wires and the filament, are housed in a glass bulb, which will be filled with an inert gas like argon. When the bulb is hooked up to a power supply, an electric current flows from one contact to the other, through the wires and the filament. Electric current in a solid conductor is the mass movement of free electrons (electrons that are not tightly bound to an atom) from a negatively charged area to a positively charged area. As the electrons zip along through the filament, they are constantly bumping into the atoms that make up the filament. The energy of each impact vibrates an atom -- in other words, the current heats the atoms up. A thinner conductor heats up more easily than a thicker conductor because it is more resistant to the movement of electrons. Bound electrons in the vibrating atoms may be boosted temporarily to a higher energy level. When they fall back to their normal levels, the electrons release the extra energy in the form of photons. Metal atoms release mostly infrared light photons, which are invisible to the human eye. But if they are heated to a high enough level -- around 4,000 degrees Fahrenheit (2,200 degrees C) in the case of a light bulb -- they will emit a good deal of visible light. Within the light bulb itself, the filament is a long, very thin wire of tungsten metal. This is used is very nearly all incandescent light bulbs, and this is because tungsten is simply ideal to use for the filament material. Most other metals would melt under such high temperatures, the structural bonds between the atoms would be broken apart by the vibrations caused by the heat, hence the material becomes liquid. Tungsten is the favoured metal to use in light bulbs because of its high melting temperature. However with that said, tungsten will set on fire when it reaches such extreme temperatures, in the right conditions. Combustion is the end result of two particular chemicals reacting with each other, which occurs when one of said chemicals reaches it's ignition heat. On earth at least, combustion is almost always a reaction between the atmosphere's oxygen, and a given heated material, but there are other chemical combinations that will ignite as well. The lightbulb's filament is encased in a sealed chamber free of oxygen, therefore avoiding combustion. In the early days of light bulbs, a near vacuum was created inside the bulb by sucking out all (or nearly all) of the air, as a result of this, there was barley any oxygen in the bulb, preventing combustion. The main flaw with this method was that the tungsten atoms were evaporating. At the high temperatures required, occasionally a tungsten atom vibrates heavily enough to seperate itself from the surrounding atoms and launches itself into the air. In the old style vacuum bulbs, the free atoms of tungsten shoot out in straight line and build up on the inside of the glass bulb. As this happens over and over again, the filament is losing atoms and therefore starts to disintegrate, and the glass gets darker and darker as it fills up with atoms. This has a massive effect on the lifespan of a light bulb. Inert gases (typically argon) are used in modern day bulbs to keep the loss of tungsten to a minimum. When an atom of tunsten evaporates, (vibrates heavily enough under the heat to split off from the filament) the likelihood is that it will reflect off an argon atom and be directed back to the solid structure of the filament. Inert gases normally do not react with other elements, it would therefore be impossible for a combustion reaction to occur inside the bulb. The modern incandescent light bulbs emit the majority of their energy as heat-carrying photons. Only around 10% of the light porduced by these bulbs in actually in the visible spectrum. This is quite a big waste of electricity. Sources of "cool light" like LEDs anf fluorescent lamps don't waste a great deal of energy producing heat, the majority of what they emit is just visible light and this is the reason that they slowly phasing out the old reliable light bulb. About the Author: |
We Build in L.A. is a Starter Plan business web site for rent for General contractors and remodelers in the Los Angeles, California.