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Re: Glass....



At 15:15 5/27/97 -0600, Larry Smith wrote:
At 9:45 AM -0400 5/24/97, von Philp wrote:
What is the difference between crown glass and flint glass?

-- Ralph von Philp

I have a related question. Which glass are the prisms we buy from Edmund,
Cenco, Pasco, Fisher, etc.? The catalogs don't say, nor does any
documentation I can find. I'm looking for the index of refraction of the
prisms in a spectroscope experiment.

Thanks,
Larry


One measures the angle A of the prism, and delta the angle of minimal
deviation for a selected wavelength, and then the refractive index
relative to air ( mu) is given by

mu = sin 1/2 (A + delta)/sin 1/2 A


Physics, Starling & Woodall, Longmans, Chapter 26, p606


But it is misleading to think of two varieties of glass, when in fact
there is a long series of glasses, ( as many as 100 from some suppliers)
with a gradation of dispersion and index due to a variety of metal
oxides...

Another thought - don't spectroscopes use diffraction gratings more,
these days?

Regards
brian whatcott <inet@intellisys.net>
Altus OK