Re: phase vs group vel.

[phrp@bigcat.fhsu.edu (Roger Pruitt)]

Wolfgang Rueckner wrote:
> > If all else fails (absence of ponds, for example) consider a film or video
> > of a boat moving on smooth water.  Better still, take them for a ride on a
> > ferry so they can see for themselves the group and phase velocities of the
> > wake.
>
> Actually, you can also demonstrate this in a ripple tank.  Float a wooden
> ruler (or any rectangular piece of wood) in the tank and give it a downward
> tap with your finger.  Do this a few times to get a good sense of what's
> going on, otherwise the student just sees the water being disturbed.
> Wolfgang Rueckner
Dr. Eric Lane had a great demo for phase and group velocity that worked
on the Apple II and was available through CONDUIT.

More recently, I've used a demo that comes with Serway, Moses and Moyer,
Modern Physics. The software disk is packed with the book but is also
available from Saunders Pub. for about $10. There are other demos on the
disk that relate to quantum mechanics, but the classical phase and group
velocity demo is worthwhile.

Roger
-- 

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|  Dr. Roger A. Pruitt         |
|  Department of Physics       |
|  Fort Hays State University  |
|  Hays, KS  67601             |
|  Ph. (785) 628-5357          |
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