[cdt-l] Black pot = increased heat

[Karen Somers]

Thermal energy is transferred by three methods,
convection, conduction and radiation.  Heating a pot
of water with a flame is by conduction, not by
radiation.  Am I right?
 
It is confusing.  I know all objects give off
radiation and absorb radiation depending on their
temperature and composition.  

I'm no physicist, but I think that, theoretically, a
black pot should both emit and absorb thermal energy
at a faster rate than a lighter colored pot.  I.e., it
should cool off and heat up faster.  

This from Wickipedia:

"Shiny materials typically reflect heat, just as they
reflect visible light; dark materials typically absorb
heat, just as they absorb visible light. In actuality,
light is another a form of electromagnetic radiation
with a shorter wavelength (and therefore a higher
frequency) than heat radiation. The difference between
visible light and radiant heat is small: they are
simply different "colors" of electromagnetic
radiation."

I don't have any idea why Mark's test did not work
out, except that perhaps this effect is negligible on
a small pot of water.  Very interesting.

Nocona

> 
> Mark Dixon <mkdixon1 at excite.com> wrote:
>   
> I've always wondered why a blackened pot would
> increase heat transfer when cooking. Nocona said it
> in the last post. Since a stove emits long-wave
> radiation, the color of the pot should have no
> effect. If you were somehow able to cook with direct
> sunlight, shortwave radiation, a black pot would
> matter. Is the black stuff acting as an insulating
> layer? Any physicists out there to explain?
> 



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