A lamp that emits visible radiation through the process of Fluorescence. Introduced in 1938 by General Electric, fluorescent lamps are more energy efficient and cooler than incandescent bulbs. Fluorescent bulbs, typically a long cylindrical tube, have an interior coated with a fluorescent material or Phosphor. Electrical current applied to the bulb excites mercury atoms inside to produce ultraviolet radiation. The phosphor coating absorbs the ultraviolet radiation and emits visible light. The distribution of wavelengths emitted depends on the phosphor selected. Some phosphors used in fluorescent lamps are: calcium tungstate, magnesium tungstate, zinc silicate, calcium silicate, cadmium borate, magnesium arsenate. Multiple phosphors are used to produce various color temperatures (CT):
- Warm white (CT=3000K) yellow-white - similar to incandescent;
- Cool white (CT=4200K) white - similar to early morning sunlight;
- Daylight-D (CT=6500K) bluish - similar to overcast day.
Fluorescent lamps are very energy efficient and have a lifetime of 10,000 hours.
Synonyms and Related Terms
fluorescent lightbulb; fluorescent lighting; Leuchtstoffröhre (Deut.); lampe fluorescente (Fr.); lâmpada fluorescente (Port.)
- Emits ultraviolet radiation. The UV level can vary from 40-250 microwatts per lumen.
- Fluorescent bulbs contain Mercury and must be treated as hazardous waste.
Resources and Citations
- T.Brill, Light: Its Interaction with Art and Antiquities. Plenum Press, New York, 1980.
- ASTM, Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials, Annual Book of ASTM Standards, Section 14, General Methods and Instrumentation, ASTM, G113, 1371-1373, Sep-94
- Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
- GE Lighting: www.gelighting.com/ns/institute/ul_last100.html - gives date for first fluorescent lamp as 1938.
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- A Glossary of Paper Conservation Terms, Margaret Ellis (ed.), Conservation Center of the Institute of Fine Arts, New York City, 1998
- Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998