[Fhsst-physics] Optics topic opinions?

[lglesene]

Mark (and/or anybody else):

The topic of apparent depth is coming up in working on the optics chapter.
 We'd like to include a way to derive the apparent depth of an object in
the chapter, but there seem to be two options, both with something nasty:

(1)  The nice result:  real depth/apparent depth ratio is the index of
refraction of water (or whatever material).  This is easy to derive, but
requires a small angle approximation.  I'm worried that the small-angle
approximation would be confusing to students.

(2)  Derive a more accurate formula.  Not bad, but ends up with a formula
involving tangents of inverse sines.  Here I'm worried that students would
get scared away by that much trig, and also the result isn't terribly
enlightening.

I guess a third option would be to discuss the topic conceptually and not
develop a formula.  Any thoughts?

Lindsay