(Ecotect教程)artificial_light.pptVIP

Lamps and Luminaires A lamp is: an electrically powered light source e.g. a buld A luminaire is: the complete lighting unit it includes one or more lamps Artificial light Incandescence is : the emission of light from a object when its atoms are excited by raising its temperature. Luminescence is : the emission of light from a object when its atoms are excited by means other than raising its temperature. Incandescense A material is heated above 0 Kelvin (-273 0C), it will emit electromagnetic radiation. The higher the temperature, the higher the frequency of the electromagnetic radiation. At around 873 Kelvin (600 0C), the object starts to glow. At around 2500 Kelvin (2227 0C), the object becomes “white hot”. Luminescence A glass tube filled with sodium or mercury vapour Electrodes at either end to create a voltage differential The vapour becomes ionised and emits electromagnetic radiation Two main types of lamps: Incandescent lamps : light is produced by heating a metal wire by passing an electric current through it. GLS bulbs Halogen lamps Discharge lamps : light is produced by passing an electric current through a gas or vapour. Fluorescent lamps (Low pressure mercury) Metal halide lamps Low pressure sodium lamps High-pressure mercury lamps High-pressure sodium lamps Incandescent lamps - GLS Bulb Usually filled with an inert gas such as argon May be decorative May have an integral reflector May have a finish that diffuses the light Has a base (e.g. screw base) that provides an electrical connection Incandescent lamps - GLS Bulb Incandescent lamps - Tungsten Halogen Also a type of incandescent lamp Much brighter than ordinary incandescent lamp Filled with a halogen gas such as bromide or iodine Tungsten atoms that evaporate combine with the halogen atoms and can not form a black coating on the inside of the bulb Incandescent lamps - Tungsten Halogen Discharge lamps - Fluorescents lamps (Low pressure mercury) Electric curr