billybushcook wrote:onservation of energy principle............if you still have 40 Watts of electrical energy being used, it has to be converted to some form of out put energy, in our case we don't want it being converted to light energy, so if you contain the light energy with in the light fitting, it will emit 40 Watts of heat energy (almost).
Not sure of your physics here, Mick.
The filament in the lamp gives off x amount of heat and y amount of light. When the globe is clear the light can pass through and some of the heat is absorbed by the globe and some passes through. When the globe is painted black the wavelengths of visible light are absorbed by the "black". Your theory infers that if I painted a more efficient light source such as a "fluoro" tube black then it would give off more heat.
The 40 watts of electricity has been used before any light or heat hits the globe. It's the filament that uses up the energy. It takes electrical energy and converts it into heat and light in a ratio depending on its "efficiency". (An old style radiator bar works on the same principle. The heater glows at red i.e. at the lower end of the light spectrum.)
Imagine the heat and light leaving the filament. The moment it leaves, 40 watts of energy has been used. It has already been "converted to light energy" (quote from Mick in the above.) It has to travel all the way to the globe, technically a barrier. This barrier will absorb some of the energy (wavelengths) and let some energy (wavelengths) pass through.
Now if we were to apply your principle to the electric radiator then it would mean that if we placed a sheet of black painted glass in front of the radiator then it would become a more efficient heating device because the red wavelengths of light would be converted to a lower frequency and thus give off more heat. I don't think this would be the case.
Think of the colour black as being equivalent to insulation batts. If you put an insulation batt between your beer and a light globe then the heat would be absorbed by the batt and none of it would get through. The black pigment is an "insulation batt" for the light spectrum...the energy is absorbed and not let through.
I like your thinking, though, because on a sub atomic level your theory is probably correct.
Cheers