Physics of Incandescent Lamp Burnout

Incandescent lamps with tungsten filaments have been in use for about a century while being gradually replaced by fluorescent lamps; in another generation both will quite probably be largely replaced by light-emitting diodes. Incandescent lamps (simply called lamps in what follows) burn out after a lifetime that depends mostly on the temperature of the filament and hence the applied voltage. A full-term project (about 100 hours) on lamp burnout was carried out by two students in 1965 and has been briefly described.1 Many aspects of the physics of lamps have been dealt with in articles that have appeared in this journal, in the American Journal of Physics, and in Physics Education.2,3