How CFLs Work
How CFLs Work | When Not to Use CFLs | Choosing the Right CFL
A fluorescent lamp contains low pressure mercury vapor that produces ultraviolet (UV) radiation when its energy level is changed. The inner surface of the lamp is coated with phosphor that emits light when struck by the UV radiation. Although CFLs contain a tiny amount of mercury the contribute on average half the mercury to the environment than the regular incandescent bulbs which they replace (since so much less coal, which usually contains mercury, needs to be burned at electricity plants to power the CFL).
The flow of energy to the vapor is regulated by a magnetic or electronic ballast. The ballast can either be integrated with the lamp (forming a single fixture - the most common CFL type these days), or it can be separate, modular design, allowing replacement of the lamp and reuse of the ballast.
Electronic ballasts enjoy several advantages over magnetic ballasts. They do not generate the irritating flicker that characterizes magnetic ballasts when the lights first are turned on. Lamps powered by electronic ballasts last longer and are more efficient. Electronic ballasts also are lighter, facilitating their use in fixtures that would be too top-heavy with lamps powered by magnetic ballasts.
Relatively long, linear or tube fluorescent lamps have been mass-produced since World War II, and have been used mostly in non-residential applications. Compact fluorescent lamps (CFLs), developed in the late 1970s, are much more compact. Available in many sizes and shapes, they can be used in most conventional fixtures designed for conventional light bulbs.
CFLs are so efficient that typically they save the consumer between 50 and 80% of the energy costs associated with the regular incandescent bulb they replace. What's more the average CFL lasts more than ten times longer than its incandescent counterpart.
Technological advances over the past few years have meant that high-quality CFLs (such as all those sold through SafeClimate) are typically indistinguishable in their functionality and light characteristics compared to the regular incandescent bulbs they replace. The only things you'll notice as being different are your lower energy bills and saved effort from having to replace the CFL bulbs so much less frequently.