Re: POLARIZATION

[brian whatcott <inet@intellisys.net>]

At 17:35 6/11/98 -0700, Leigh answered this question as follows:

> > So can one account for the phenomenon (of polarization) in terms of the
> > interactions of spinning photons with the polarizer?
[Leigh]
> If one considers the interaction of a circularly polarized
> photon with a (dissipative) linear polarizer, then its
> angular momentum is absorbed by the polarizer whether it
> is transmitted or not.

This statement appears to be completely in error, if by circular 
polarization of a single photon one is referring to its spin.
 A photon has spin or it is not a photon.
 I expect Leigh had some other meaning in mind.


> ...The stupid "slit" model (which I assume is equivalent to the
> cake-grid or picket-fence model) is outrageously misleading.
> A student should go away "understanding" that the light is
> polarized in a plane parallel to the highly conducting grid?
> When she actually tries it in the lab with microwaves and a
> real cake grid she will find that the plane of polarization
> is at right angles to it - or else she won't be able to
> understand what is going on at all because of the fixed idea
> that the wires must be parallel to the plane of polarization.

I find this statement too, misleading.
There are cake grids, and cakegrids.....

 Here is a useful counterexample which I mentioned here in the last 
week or two:
For any "cakegrid" of conductors arrayed in a horizontal direction
which can be demonstrated to pass vertically polarized radiation,
I can be pursuaded to produce a metallic array of VERTICAL conductors
which can be demonstrated to pass vertically polarized radiation, 
which I suppose could make Leigh's illustrative analogies similarly 
fatuous.

 The comparison is between broadside dipole arrays, and broadside 
slot arrays, in terms of radio antennas.
 Slots and ordinary dipoles are complementary structures distinguished
by the conductivity of the surrounding medium: high and low respectively.
 Their major dimension is mutually orthogonal to the other's for the 
same output polarization....



> I have seen this misconception manifest more than once in a
> laboratory situation (and mostly with male students). Score
> another triumph for "conceptual" physics over real physics.
>
> Leigh

Hmmm....perhaps Leigh's male students are more insightful than 
his female students?  :-)

Brian Whatcott    Altus OK