Materials Used in a Light Bulb
The electric light bulb has been in existence since the late 19th century. Until the early 2000s, incandescent light bulbs were the standard in home use, while fluorescent lights were used mostly for offices and other commercial establishments. Halogen and neon lights are less commonly used. However, beginning in the early 2000s, compact fluorescent light bulbs began to appear in homes as well. Depending on the type of light, the materials used may vary; however, some materials are common to all types of light bulbs.
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How Light Bulbs Work
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While light bulbs may vary by shape and function as well as the materials used to make them, they all work in roughly the same way. All types of light bulbs work by the reaction of the introduction of electric current to whatever lighting element is contained inside the bulb. When the lighting element is activated by the electric current, it gives off light. Eventually, the interaction of electricity with the lighting element will extinguish the lighting element, at which point the bulb will no longer emit light. In common vernacular, the bulb will have burned out.
The Casing
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Nearly all light bulbs are formed with a glass casing. The glass may be coated or frosted depending on the type of light bulb. The shape of the casing may also vary: Incandescent light bulbs are small and round in order to fit in household sockets. Fluorescent lights are often long and thin tubes. Halogen light bulbs may be broader than conventional incandescent light bulbs, while neon lights are manipulated into many different shapes. Compact fluorescent light bulbs usually have twisted tubes that are shaped into a compact form to allow them to be used in household sockets originally designed for incandescent bulbs.
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Lighting Element
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Light bulbs also need a lighting element. For incandescent bulbs, the lighting element is a tungsten filament that heats up when electric current flows through it. In fluorescent bulbs, the lighting element is mercury vapor, which emits ultraviolet (UV) energy in the form of light. This is true for both conventional fluorescent lights and compact fluorescent light bulbs.
Inside the Glass Casing
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The major challenge that was overcome in the development of the light bulb was eliminating oxygen inside the glass casing. In incandescent light bulbs, oxygen has been vacuumed out of the glass casing. In fluorescent light bulbs, oxygen is replaced with a phosphor coating that contains mercury vapor. What are commonly called neon lights may in fact contain neon, argon or mercury or phosphor coatings that vary according to the color desired for the neon lights.
Considerations
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All fluorescent bulbs, including compact fluorescent bulbs, contain at least some mercury, which has presented a problem in disposing spent bulbs. However, compact fluorescent bulbs last far longer than incandescent bulbs, which is one reason the European Union (EU) has mandated that conventional incandescent lights will be phased out of use by each of its member states by September 2009. Halogen lights are extremely hot and may present a fire hazard if allowed to run unattended for long periods.
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