> The manufacturers already make "long life" bulbs.  It appears
> that these use
> beafier filaments that run a little cooler.  Note that the
> light output of
> these bulbs is less than the normal ones at the same wattage.  In
> otherwords, they traded efficiency for life, which is what
> you are doing
> with the resistor.

Efficiency is strongly influenced by filament temperature.

Someone has a "Miser" series of lights that put out more visible light
per watt than regular bulbs.  They do this by polishing the filament
wire so that it is a poorer black body radiator.  To radiate the same
amount of power the filament has to get hotter than regular filament
would.  A hotter filament means you get more visible light and less
infra-red per watt.

This is good for efficiency but shortens the filament life due to the
tungsten evaporating faster.  It saves you money because you don't have
to buy as much electricity, but you have to change bulbs more often.
The electricity costs more than the bulbs.  In theory it is good for
you, good for the bulb company shareholders, but bad for the electric
company shareholders.  It is also a pain to keep chainging bulbs.

Sherpa Doug

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