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Old 01-June-2005, 02:29 PM
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Quote:
Originally Posted by lyndonashmore
I think we have covered everything on this point now, so how do free electrons with random thermal motion generate 'density waves?"
The same way they do it in a metal.
The electrons cannot leave the volume occupied by the plasma.
If they try, a net positive charge arises, and they are pulled back.


Quote:
Originally Posted by lyndonashmore
I say it is because the individual electrons perform SHM and there is a phase lag between them so we get the 'density waves'.
What do you say?
You are wrong.
The electrons do not oscillate about an equilibrium point. They fly around in the plasma.
If they were oscillating about a point, they would be bound to it (like in an atom), and there would not be a plasma.

Do you remember the analogy with sound?
The air molecules have Brownian motion, yet we can have oscillations in the pressure, on length-scales much large than the average distance between the molecules.


Quote:
Originally Posted by lyndonashmore
Lyndon With profound appologies to Papageno.
What are your apologies for?
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