Re: REFRACTION - REFLECTION

["Rauber, Joel Phys" <RAUBERJ@mg.sdstate.edu>]

While the answer below is perfectly adequate, I'm not sure I'd want to use 
it as an answer to a high school class.  Are there any good, more level 
appropriate explanations out there?

Joel
 ----------
From: Dr. William Newbolt
To: QuistO; RAUBERJ; phys-l
Subject: Re: REFRACTION - REFLECTION
Date: Friday, January 09, 1998 8:48AM


We discussed total internal reflection in my high school
class this week and one student had a question I was not
sure about answering. He asked:

It is relatively easy to understand the macroscopic
interaction light has as it passes from water to air and
bends as it does so due to a change in the velocity of the
light. But, what is the interaction that occurs if the light
reaches the surface with an angle of incidence greater than
the critical angle? What is really happening in this
situation and how is it different from the situation when
the angle is less than the critical angle?

I was not sure how to answer, can anyone help?  Thanks. --
David Abineri     dabineri@dot-net.net

In general both refraction and reflection occur at an
interface.  You can calculate the intensity of the two
beams using the boundary conditions on electric and
magnetic fields at the boundary of a dielectric and the
angles.  At the critical angle it just becomes inpossible
for any of the radiant energy to appear in the refracted
beam and all of it is reflected. You can get this from
boundary conditions, but it is too long and messy to
write out here.  See any good E&M book that talks
about the properties of electromagnetic waves.   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
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