[Amps] making sinks black

[slifamily]

Roy wrote:


>  Black bodies radiate and absorb heat many times 
> more efficiently than a white or shiny body.

I have heard it said that this is largely true at extreme
temperatures.  Might be nice to have someone dissipate a
"real world" amount of power (say 100 watts) in a heat
sink of raw aluminum and do it again with an identical
sink that is black.  I have a hunch that the heatsinks will
have similar temperatures.

Check out this website for a pretty good discussion of emissivity of heat.
You might be surprised to see what a difference the material and color
makes.

http://x26.com/irpaper_emissivity.htm

The emissivity of anodized aluminum is typically very poor.  The same
material painted flat black is very good.


>  Try wearing a nice black tee shirt in the direct sun as 
> compared to a white one.

Absolutely no question here but isn't this a case of 
absorbing heat as opposed to radiating it?

The property applies in both cases

- Jim WB6BLD


Steve
KT4FY