What is the difference between a mercury vapor lamp and a metal halide lamp?
A mercury vapor lamp is a type of arc lamp where the arc passes through vaporized mercury.A metal halide lamp is an extended life version of an incandescent filament lamp, the life of the filament is extended by a halogen gas fill that scavenges metal that has vaporized from the filament (which causes the filament to thin and weaken) preventing it from depositing on the glass envelope (darkening it) and the metal halide compounds produced decompose on contact with the hot filament depositing metal (building back up the weakest parts of the filament) and regenerating the halogen gas fill.
