"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in message
...
How can running hotter be more efficient? I would think for a light bulb,
the most energy dissipated as heat rather than light, the less efficient
it
would be.

First, the hotter, the higher the content of visible light. The spectrum of
emitted radiation simply moves up to shorter wavelengths when the filament
is hotter, therefore a larger portion is in the visible range and less in
the IR range.

For halogen bulbs, the temperature has to be high enough to keep the
tungsten recycling process running. When too low, the emitted tungsten
condenses on the cool glass. When the temperature is high enough, the
tungsten does not condense on the glas but returns to the filament.

Meindert