Why do some halogen light bulbs last longer than a regular incandescent light bulb?
Both regular incandescent bulbs and halogen bulbs create light by heating a tungsten filament. Usually, the bulb burns out when the filament is fully depleted. The filament in a regular incandescent bulb burns out over time because the tungsten on the filament evaporates and is redeposited on the bulb’s glass. Those tungsten deposits are the reason bulbs often appear darker when they burn out. Halogen bulbs can last longer because the halogen gas and intense heat inside the bulbs redeposit the tungsten back onto the filament as it evaporates, known as the “halogen cycle”. A halogen bulb will still eventually burn out because the filament becomes too stiff and brittle to sustain the vibrations caused by re-lighting.
