 GeneralWhat is a Fluorescent Tube ?Fluorescent light has been available since the late 1940s. Until fairly recently it was only available in a linear "tube" form that did not easily lend itself to many domestic applications. Also, fluorescent lamps require control gear to operate and the quality of light tends to be harsh and unappealing, unless contained by a special housing or hidden from view. For this reason its use was restricted to the garage or utility room. Thanks to developments in electronics, chemistry and innovative design however, the commonly held prejudices against fluorescent lighting have to some extent become invalid. For example, the flickering associated with fluorescent lighting on switching on has largely been overcome by modern electronic control gear. Special controls allow dimming of fluorescent lighting and developments in phosphor coatings have created a large range of colour temperatures from the equivalent of warm "tungsten filament" to cold "daylight" temperatures. Unlike tungsten filament or incandescent light sources, a fluorescent tube does not produce light by heating a wire filament. At each end of the glass tube are electrodes. The glass tube contains minute droplets of mercury and an inert gas. When a high voltage current is passed across the electrodes it produces an "arc" or flow of current along the length of the tube and by chemical reaction this creates ultra violet radiation. The inside of the tube is coated with phosphor powder and it is the excitement of this coating by the ultra violet radiation that produces the visible light. The system is efficient, cool running and long lasting. Because the quality of light is diffuse and lacking "sparkle" it cannot be focussed in the way that tungsten, tungsten halogen, LED and some other discharge sources can. SEE ALSO "What are Compact Fluorescent Lamps?" "What is the correct way to dispose of lamps ?"
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