The standard incandescent bulb, invented in 1879, was the first type of electric lamp and is sometimes referred to as the Edison bulb named after its inventor, Thomas Edison. This technology is still the mainstay of lighting despite being the least efficient of the lighting technologies. A typical 60-watt incandescent bulb has a life of about 750 to 1000 hours and emits light that has a color rendering index (CRI) of close to 100%. It is available in many different versions from miniature lights for a Christmas tree to powerful flood lamps for area lighting. It has the advantage of providing light instantaneously even in cold temperatures. The light emitted is in the center of the light spectrum. The standard general purpose bulb is no longer manufactured and has been replaced with the tungsten halogen bulb as part of the Energy Act of 2005.

A tungsten halogen lamp is a type of incandescent lamp that is 27 percent more efficient than a standard incandescent bulb and has a life of 2000 to 6000 hours. This type of lamp is well suited for general purpose indoor or  outdoor area lighting controlled with a photo/motion detector control. They will be phased out in 2020 as part of the Energy Act of 2005

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Scott Sanford, Distinguished Outreach Specialist, University of Wisconsin, sasanford@wisc.edu.