Re: The Crookes Radiometer
- From: Richard Saam <rdsaam@xxxxxxx>
- Date: Fri, 15 Aug 2008 17:29:07 +0000 (UTC)
Wortman wrote:
In article
<g6n5l3$9u9$3@xxxxxxxxxxxx>baez@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (John
Baez) wrote:
It seems there's still a lot of mystery about how this gadget
works. If you have thought deeply about this issue, try:
possible answer in terms of
ratio of material radiation to black body radiation emissivity
and associated material absorptivity.
at 298 K black body radiation is ~450,000 erg/cm^2/sec
maximum at wave length ~9.7E-04 cm
and energy density of ~6E-05 erg/cm^3
and force 1/3 energy density or ~2E-5 dyne/cm
http://en.wikipedia.org/wiki/Radiation_pressure
material (empirical data from Perry engineering handbook)
black carbon emissivity ~.8 or radiation ~360 watt/meter^2
polished silver emissivity ~.02 or radiation ~9 watt/meter^2
I do not have numbers
for corresponding material empirically observed absorptivity
but surely they exist.
It would be difficult to generate these numbers from first principles.
The Radiometer is all one temperature
with different selected material emissivity/absorptivity surfaces
responding to incident radiation
with associated differential forces.
These material absorptivities and emissivities
(and influenced by any adsorbed gases)
vary with temperature
so it is conceivable that the Radiometer rotation
would be a function of temperature
(maybe one way and than another f(Radiometer temperature)
and the resultant emitted radiation from all surfaces
would equal the incident radiation.
Black Body theory was developed
after the time of Reynolds and Maxwell
These are probably some of the thought processes
used by the team analyzing the Pioneer 10 & 11
archival data, establishing the radiation force vector
relative to the deceleration anomaly
Richard D. Saam
.
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