halogen bulbs

Halogen bulbs are high pressure, incandescent bulbs that contain halogen gases such as iodine and bromine that allow filaments to work at higher temperatures and higher efficiencies. Halogen bulbs consist of a tungsten filament inside a quartz envelope that is filled with halogen gas. In halogen bulbs, the quartz envelope is closer to the filament than the glass used in conventional light bulbs. Heating the filament to a high temperature causes the tungsten atoms to evaporate and combine with the halogen gas. These heavier molecules are then deposited back on the filament surface. This recycling process increases the life of the tungsten filament and enables the halogen bulb to produce more light per units of energy. Consequently, halogen bulbs are used in a variety of applications, including automobile headlights. Halogen bulbs are an example of a low-price technology that proves to be costly over the long term.