<Li> High pressure sodium lamps, producing up to 150 lumens per watt . These lamps produce a broader light spectrum than the low pressure sodium lamps . Also used for street lighting, and for artificial photoassimilation for growing plants </Li> <Li> High pressure mercury - vapor lamps . This lamp type is the oldest high pressure lamp type, being replaced in most applications by the metal halide lamp and the high pressure sodium lamp . It requires a shorter arc length . </Li> <P> A high - intensity discharge (HID) lamp is a type of electrical lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube . Compared to other lamp types, relatively high arc power exists for the arc length . Examples of HID lamps include: </P> <Ul> <Li> Mercury - vapor lamps </Li> <Li> Metal halide lamps </Li> <Li> Ceramic discharge metal halide lamps </Li> <Li> Sodium vapor lamps </Li> <Li> Xenon arc lamps </Li> </Ul>

Why does neon gas in a tube fluoresce bright orange when electricity is passed through it