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Re: EM Ranges...



Date: Wed, 17 Dec 1997 15:31:09 -0500 (EST)
Reply-to: phys-l@mailer.uwf.edu
From: crvhs_dks@ncocc.ohio.gov
To: physhare <physhare@lists.psu.edu>
Cc: Physics Listserver <phys-l@atlantis.uwf.edu>
Subject: EM Ranges...

Greetings everyone. I'm trying to prepare some material
for later
on in the year for my physics students dealing with light
(em spectrum). A couple of things I've noticed is that from
textbook to textbook the frequencies and wavelengths tend to
range quite a bit. I realize that there is no clear
division between one continuous spectrum to another, but I
figured that there may be some ranges.
Also, I've noticed in some sources that the multiples of
the
frequency and wavelengths are not always equal to speed of
light (c). Some, when multiplied out, gave me answers that
were almost 1/3 to 2/3 of c.
Does anyone have a listing of the em spectrum with the
various
wavelengths and frequencies that they use? Are my sources
way off track or is there just some "room to play" with the
numbers?

Dwight
Ashland, OH

Sound to me like you might be dealing with propagation in
different media. The frequency times the wavelength should
be the speed of the wave movement in the medium you are
considering. Also, you may not be dealing with
monochromatic sources in which case you have to worry about
the group velocity as well. By the way, for some
wavelengths the atmosphere is dispersive. For
these wavelengths the speed is not c, but is c/n where n is
the index of refraction for the propagation medium. WBN
Barlow Newbolt
Department of Physics and Engineering
Washington and Lee University
Lexington, VA 24450
Telephone and Phone Mail: 540-463-8881
Fax: 540-463-8884
e-mail: NewboltW@madison.acad.wlu.edu

"Prediction is very difficult, especially about the future."

Neils Bohr