What is a fluorescent lamp?

   A fluorescent lamp is a source of artificial light produced by bombarding a phosphor with ultraviolet light. The phosphor is the heart of the lamp, for it converts shortwave ultraviolet radiation into visible light. (A phosphor, by definition, is a substance that gives off light when struck by suitable radiation, usually ultraviolet light.)
   Fluorescent lamps for household use are available in a number of different colors. Compounds of calcium, sulfur, phosphorus, and other materials are carefully mixed to produce light of daylight quality or various tints.
   A fluorescent lamp is made in the shape of a tube, the inner wall of which is coated with the phosphor. The tube is usually filled with argon, with a small amount of mercury; the amount of mercury and the pressure are adjusted to produce a considerable amount of ultraviolet radiation at 2,537 angstrom units wavelength; this is a frequency that is efficient in causing fluorescence in the phosphor materials used. At each end of the tube is an electrode. When electrons are made to flow between the electrodes by a proper voltage of electric current, the mercury vapor produces ultraviolet radiation. This radiation, in turn, makes the phosphor coating give off visible light.