dave@onfcanim.UUCP (Dave Martindale) (07/05/86)
In article <384@twitch.UUCP> grt@twitch.UUCP ( G.R.Tomasevich) writes: >> Some friends of mine noticed, while juggling clubs under a >> chandelier, that a light bulb, when hit just right with a club, >> will become very bright. By "very bright", I mean that a large > >The filament bent around on itself and shorted out. Since the remaining >part runs much hotter, the tungsten evaporates at a significant rate. Now, >if you put some iodine inside the bulb and make the envelope out of quartz, >it will last longer a la 'quartz-iodine' or 'halogen' lamp. There's one key thing missing - the bulb has to be quite small in order to be close enough to the filament to get quite hot. If it remains cool, tungsten deposits on it just like in a normal bulb, it slowly gets dimmer, and soon dies. If the bulb envelope is above a certain temperature, the iodine reacts with the evaporated tungsten and re-deposits it on the filament, keeping the bulb clear and greatly slowing down deterioration of the filament. The bulb has to be quartz simply to stand the high temperature without melting.