4 ms·

Any bulb? I'm biased. I like that they run a webcam: http://www.centennialbulb.org/cam.htm http://www.centennialbulb.org/cam.htm Where'd you get the 1/4 volta

• pjc50 12y ago
  Not quite any bulb. Tungsten filaments evaporate over time, carbon filaments don't. But carbon filaments are much more fragile if subjected to thermal cycling or vibration.
• CamperBob2 12y ago
  http://en.wikipedia.org/wiki/Incandescent_light_bulb http://en.wikipedia.org/wiki/Incandescent_light_bulb , under the Light Output and Lifetime subhead. Lifetime is approximately proportional to the 16th power of the voltage, according to that article. 1/4 was a randomly made up figure (and probably wouldn't even result in a visible glow with many bulbs) but if you could see the light from such a bulb, it would presumably last up to 4 billion times longer than normal. By the same token a 5% reduction in voltage will double the life of the bulb. So it wouldn't be hard at all to find a voltage somewhere in between that will allow an ordinary incandescent bulb to emit visible, maybe even useful levels of illumination, while lasting 100 years or more. As others have mentioned, the Centennial bulb doesn't exactly emit useful levels of light. If I'm doing the math right, if you took a 100W/120V incandescent bulb rated for 1000 hours and scaled down the voltage by the 16h root of 876, or 80 volts, its life expectancy would reach 100 years. The bulb would use about half the power be about 1/4 as bright as normal. Its color temperature would obviously be pretty awful, but the Centennial bulb doesn't excel in that department either.