Compact Fluorescent Bulb Basics

• Compact fluorescent light bulbs (CFLs) are newer, smaller versions of the old fluorescent bulbs. They are designed to fit into the light sockets used by normal incandescent bulbs. Because fluorescent bulbs use less energy than incandescent, CFLs are being phased in and incandescent lights are being phased out. Like all fluorescent light bulbs, CFLs contain a trace amount of mercury, which is crucial to the operation of the bulb.
  
  

Compact Fluorescent Lights Structure

• A compact fluorescent light is a bent tube with electrodes at either end. The tube is filled with argon gas and a small bit of mercury. When the CFL is turned on, electricity flows through the argon gas. Some of the individual electrons strike mercury molecules. When they do, the mercury molecules absorb energy from the electrons.
  
  

Making Light

• The mercury then discharges this energy as a photon of ultraviolet light. Ultraviolet light is similar to visible light, but it is outside of the visible spectrum. The ultraviolet photons inside a compact fluorescent light strike a phosphor coating on the inside of the bulb. This phosphor coating works a bit like the mercury molecule does -- it absorbs the energy from the photon and re-emits it, this time as a photon of visible light. Without the mercury to create the original ultraviolet photon, the fluorescent coating wouldn't be able to produce visible light.