On Mon, 03 May 2010 18:28:25 -0700, Jim Lux
wrote:

Roy Lewallen wrote:
Jim Lux wrote:

Hi Jim,

Much of what you write looks like stream-of-consciousness writing.
Did/do you have a point?

The plastics degradation is definitely an "athermal" effect (because
adding carbon black to the plastic inhibits it, but doesn't change the
absorbed power very much.

UV radiation has migrated awary from electron/atom issues to
molecular/ionic bond issues. Calling it "athermal" seems to be
returning the discussion to the metaphysical.

But..
note that the scale is in wavelength and the energy is "per nm" (because
that's how spectrophotometers work). the photons have less energy at
lower wavelength. (or, you could plot it in frequency, and then look at
the watts/Hz to integrate)

What is the significance of changing from wavelength to frequency?
(But?)

If you look at power spectral density (e.g. watts/hz) it actually peaks
up around 1000 nm (near IR). The Wien displacement law says that 5250K
peaks up at about 550 nm, but the power spectral density at 550nm (545
THz) is about 2/3 that at the peak.
By the time you get to 350nm (857 THz), the energy per hz is about 10%
of what it is at the peak (at 950nm)

Running a quick numerical integration... (multiplying the power spectral
density every 50 nm by the frequency range).. I get 0.166 for all
wavelengths shorter than 320nm, 2.09 for 320-670, and 3.6 for 670-4000 nm
(there's a missing integration constant, so the numbers have some scale
factor, but the relative amounts should match..)
for the band around 400nm, I get .26 and for the band at 550 about 0.34
and for around 650 about .32... Yes, it peaks at 550 nm as expected.

Without going into the math, it seems like you disputed a figure you
then discover "as expected." What was the dispute? What wasn't
expected and then came as a surprise?

73's
Richard Clark, KB7QHC