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Re: glass ...



On May 30 Oren Quist wrote:

We know they have different indices of refraction, but what is different
with the glasses that is responsible for the differences in the indices?

This is a very intersting new question and I hope somebody will be able
to answer it in a form which can be translated into lecture notes for an
introductory physics course. Let me phrase the question in a slightly
different form.

The index of refraction is c/v. Why is the speed of light different in
different materials? Why does it depend on frequency? How can very small
changes in chemichal composition "a few ppm of impurities" produce
significant differences in the macroscopic properties of glass?

I usually wave my hands saying something about "resonance frequencies of
molecules and atoms" and hope nobody asks me to be more specific about
SiO2 and about things disolved in it.
Ludwik Kowalski