What Makes Light Bulbs Glow?
When a light comes on at the flick of a switch, or upon opening an appliance door, or by motion alone, it is something you have come to expect. Few look at a light bulb and wonder how it works, what makes it glow and give off light. A glance inside an unlit clear bulb doesn't reveal much, not even any moving parts. So how does it emit light? Does this Spark an idea?
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The Simple Process
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Inside the bulb is a wire that goes to a piece of coiled tungsten (a heavy metallic element). This causes maximum resistance to the electricity flowing through the wire. The resistance causes the tungsten to heat up to 4,500 degrees F. A white hot reaction occurs that you see as light. The glass bulb surrounding it contains an inert gas, protecting the filament from oxygen which would cause it to burn out immediately and also prevents contact with the white hot metal.
Incandescent Bulbs
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The standard lights around your home use the incandescent light bulb. The light produced is a steady even light. These bulbs have a usable life of 700 to 1,000 hours. While the light inside does not change, special coatings on the bulb can produce bulbs in many colors, either to diffuse the light or create a different lighting appearance. Invented in 1879 by Thomas Edison, they remain virtually the same.
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The Halogen Bulb
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Halogen bulbs are used when you want a bright white light. Inside the glass bulb is halogen gas, not the inert gas found in incandescent bulbs. You need to use caution when using halogen bulbs. Even though they are brighter and more efficient than incandescent, they are much hotter and care must be used regarding their placement. It's important to note that the oil from your fingers can weaken the glass and decrease the bulb's useful life.
Fluorescent Bulbs
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Fluorescent bulbs are the most complicated of the bulbs you use. They need a ballast in order to work. The ballast is a device that regulates the electrical current coming into the bulb. These glass tube bulbs are coated inside with phosphor. Compact fluorescent lights or CFLs are now available to use in your home. Costing less to operate, yet providing the same amount of light, they last almost 13 times longer than incandescent bulbs.
Phasing Out Incandescent Bulbs
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On the September 2009 blog of ABC News it was reported that in an effort to save energy and combat global warming, the European Union began enforcing a ban on incandescent bulbs. Cuba and Australia also have a ban on incandescent bulbs. The United States plans to start phasing them out in 2012.
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