Quartz-halogen bulb

A bulb with an inner quartz bulb which holds a tungsten filament. Usually the inner bulb contains an inert gas such as iodine or one of the other five halogen gases. The use of a halogen gas prevents the bulb from turning black and thus reducing the amount of light output. Because this type of bulb requires intense heat, a quartz inner bulb is needed instead of glass. As a result, the quartz-halogen bulb produces more light per watt of electrical power. When replacing a quartz-halogen bulb, it is important not to touch the outer bulb with your fingers. The moisture and oils deposited on the glass will cause the glass to break under the high temperature.