Thomas Edison began selling his incandescent lamp in 1880 and only a few years later introduced a version with a silver coating on the back that served as a reflector. Almost exactly 100 years later (1981) Philips began selling their SL-18 compact fluorescent lamp and within a few years introduced a version with a built-in reflector—the lamp seen here.
Reflector lamps have been most often sold as either spot lights that throw a narrow beam of light, or as flood lights that throw a broader beam. Engineers alter the shape of the reflector to create different beam patterns. In an incandescent lamp they typically place the filament at a focal point so as to get as much light as possible to travel along the path they've designed. Making a compact fluorescent reflector lamp was something of a challenge since the folded-tube that radiates the light is long and is not considered "a point-source" of light. The ridges seen on the outside of the silver reflector also appear inside and help direct the light from the tube out of the lamp.
Lamp characteristics: Brass, medium-screw base with plastic skirt that houses a magnetic ballast, and a starter. Fluorescent tube includes two electrodes, mercury, and a phosphor coating. An R-shaped plastic envelope serves as a reflector and is enclosed with a plastic cover. Rating: 18 watts, 120 volts.
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