The structure of tungsten
In order to increase the service life of the light bulb, you can lengthen the wire length.
Heat distribution within the more space, but can reduce the temperature of the filament,
will naturally have less sublime, also extended the life of the bulb. But because the
temperature is reduced, resulting in visible light emitting efficiency is also reduced.
Light bulb becomes darker, requiring a higher wattage bulbs to produce the same brightness.
While increasing the service life of the light bulb saves money, but wasted energy is worth,
it's worth considering. Long-life light bulbs typically use more cost-effective in the place
is not easy to replace light bulbs. If filament length is longer, the temperature cooler, even
only the faint light of the dark will be issued, but obviously still feel issued by heat (infrared).
Early photography using the Flash in order to be closer to the Sun's spectrum, so reducing the
filament length, to work at higher temperatures, so its life is shortened a few hours of work.
(Incorporated into filaments of gas, making the spectrum of is equivalent to about 4,500 black-body
spectrum – higher than the temperature of the filament)