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Re: Path of light...



Dwight K. Souder says:

Greetings everyone. I overheard someone trying to explain how
light propagates. They stated that the electrical and magnetic waves
move perpendicular to one another. The resultant is a spiral wave. He
then went on to demonstrate with a cord of the magnetic wave moving side
to side and the electrical wave moving up and down, then with the light
wave, the end of the cord was spun around in a circle producing a
spiralling wave down the cord.

I don't see how the E- and B- parts of the EM wave can be meaningfully
added together to get a "resultant." Wouldn't that be like adding a force
and a velocity?

Sounds like maybe the demonstration was supposed to show a useful mnemonic
for how the E- and B- parts go together, rather than to show a physically
meaningful combination. After reading Bill Beaty's message, though, I
guess it didn't even get that right.

--
--James McLean
jmclean@chem.ucsd.edu
post doc
UCSD