Why do 5 year lightbulbs only last 90 days?
813352
Same reason, "til death do us part" usually means ," Til I see someine else I like better."  Not many things in life are as advertised.
1176231
Generally, light is created when energy is released, usually in the form of heat. The reason a light bulb works is because electricity (energy) is forced through something with higher resistance (the filament inside the bulb). This creates heat and as a by product, light.
485969
There are lots of different types of stars, all with different 'lifespans'. Ours is about 4.5 Billion years old and should 'live' to the ripe old age of about 10 Billion years old.
158612
Over time, the metal of the hot glowing filament evaporates.  A light bulb typically fails upon lighting, because the filament becomes too thin to withstand the mechanical stress of thermal expansion due to the rapid heating.  Repeated on/off cycling also fatigues and wears out the filament, leading to early failure.
165350
wattage of the bulb is important...prob not generating enough heat to make the 'lava' flow (wax).\n\nIt should show signs of flow within an hour...at least!
72627
isn't it usually 4 years?
525064
70 wouldnt last very long...
655179
Some can live up to a month, but some only live a matter of hours or days.
920256
5 years, is the norm,
375923
The sun is a powerful thermonuclear device.  Very little will withstand exposure to sunlight forever.\n\nTypical modern plastic based solar cells will last for 15 to 20 years.  "Glass technology" can be extended to 25 to 30 years.  Premium quality last as long as 50 years and counting.
1168094
some do \nsome don't\nTry\nmost usually "churned" every 90 days
699871
One lasts the other one don't.
659307
it depends on the size of the bulb, doesn't it?  many different sizes and shapes of bulb..... i'm not sure if there is a size of bulb that every person could 1) fit in their mouth but 2) not remove.  if there is, they should call it the "universally bad idea to stick in your mouth bulb, extra soft lighting 60watt."\n\nanother option would probably be remove the teeth, that would be my guess regarding what's getting in the way.\n\nvery appropriately timed question, as i just replaced two bulbs that had burnt out.\n\nhow many ecluv7's does it take to screw in a lightbulb?  only 1/2, because i do two at once.  :)
954358
Its the same principle as a welding arc. when the bulb goes out the philament breaks into two pieces. When they split apart, before they get too far apart, the electricity jumps the gap causing a bright flash. After that the current cant make the leap so the bulb is dead.
1073127
A lightbulb is a very cheap effective producer of heat!  Use something like a 15 to 25 watt bulb and make sure it holds the temperature steady at the correct level so you don't fry your eggs or they don't get cold.\n\nBTW a 100W lightbulb gives off 2% of the energy in light and guess what the other 98 watts are?  HEAT!
703428
It used to be like that with fluorescent lights only, but not anymore.  See this article.\n\nhttp://www.eweb.org/business/energy/energysmart/ebd/9811/lighting_myth.htm
507766
depends on the type of bulb, For incadesant bulbs thee is NO extra power required, they get hot, they glow. For florescent tubes it can be quite long, certainly of the orer of hours. once up and running they use very little