Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: POLARIZATION

At 21:56 5/28/98 -0400, Ludwik wrote:
On 28 May 1998 19:33:24 Hugh Logan <hlogan@ix.netcom.com> wrote:

There is also a series of lecture demonstrations of elliptical and
circular polararization (mechanical analogies, microwave, and optical)
from the University of Maryland starting at
(http://www.physics.umd.edu/deptinfo/facilities/lecdem/m9-01.htm ).
Just press the "next demo" button to see successive demonstrations.

... I have a conceptual difficuly with the so-called
"rotation of the plane of polarization" in some transparent materials.
Each layer of oscillating electrons turns the vector E by a small
angle, always in the same direction. Why? The usual answer "this is
caused by molecular structures of atoms" is not sufficient. What
prevents electrons from oscillating in the plane of E, as in glass or
in water? We add some sugar to water and the vessel behaves differently.

Ludwik Kowalski

It is not difficult to configure an array of dipoles, yagi style, so that
the polarization angle is changed. Just a matter of geometry of conductors.

In stereo chemistry, stereoactive materials are classified as
configurational, geometric and confirmational isomers which involve either
chirality (handedness, or non superimposability of a mirror-image) or
rotation of some part of a molecule round a double or single bond.

Achnowleging that at some level this optical activity has to be described
by the angles of charge motion, I still find no great difficulty in
accepting some mechanism of this kind.

I fancy Ludwik finds a solid crystal array a more challenging object for
didactic description. One would hope that adjacent bonds are disposed at
angles which provide a natural 'corkscrew' path through the material (i.e.
a natural progression of charge carrier angle of oscillation) - though I
expect there is more than one mechanism for providing a preferential angle
of transmission through adjacent layers.

Perhaps I am too easily pleased, but these details are essentially just
'engineering' of the natural kind, to my way of thinking....

Brian Whatcott Altus OK