Fluorescent lighting is not new.

It has been available commercially since the 1940s when a patent for an improved and practical version of the technology was issued to George Inman, a scientist working for General Electric.

Fluorescent lamps work on a very different principle than the incandescent light bulb invented by Thomas Edison in 1879. In the incandescent bulb, electricity heats a filament typically made of tungsten, an element that is resistant to the passage of electricity. The resistance results in high temperature, causing the filament to glow and emit light.

In fluorescent lamps, light is not created by heat. It results from the electrical stimulation of mercury and phosphor atoms in a sealed glass tube. The tube contains a small amount of mercury and an inert gas, typically argon. The tube also is coated on the inside with phosphor powder. As electricity flows through the tube, some of the mercury is changed from a liquid to a gas, releasing ultraviolet light in the process. The phosphor coating serves to convert the ultraviolet light, which our eyes don't register to visible light.

Incandescent bulbs also emit ultraviolet light, but do not convert any of it to visible light. Incandescent lamps also lose more energy through heat emission than do fluorescent lamps. Consequently, a lot of the energy used to power an incandescent lamp is wasted.

Overall, a typical CFL is up to 6 times more efficient than an incandescent bulb casting similar levels of light.

Today, fluorescent lamps are universal. They come in many shapes and sizes and are used for both general illumination as well as specialty applications ranging from photocopying to bug zappers. Perhaps most familiar are the 4-foot linear tubes that have long been used for illumination in schools, office buildings, warehouses and stores. Fluorescent lighting also has long been used to illuminate some residential spaces such as home workshops, kitchens and basements, but widespread use in the living area of homes has been constrained until recently by two factors.

First, people generally prefer the "warmer" light of incandescent bulbs, which produce a light with more red and less blue than that given off by the phosphor in fluorescent lamps. Second, fluorescent lamps have not been available in sizes that fit in traditional home lighting fixtures.

These limitations largely have been overcome in the last decade by rapid advances in CFL technology. Screw-based CFLs that can be used in any fixture that accepts an incandescent bulb are now available in many sizes and wattage's. The light quality of CFLs also has been improved by varying the mix of phosphors.

 

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