Question

How do you find the index of refraction?

Answer 1

refractive index = sine(incident angle)/sine(refractive angle) ...?

Answer 2

HOw do you identify the angles?

Answer 3

Here is an example I found over in the internet.

A ray of light has an angle of incidence of 36.0 degrees on a block of quartz and an angle of refraction of 20.0 degrees. What is the index of refraction for the block of quartz?

refractive index = sine(incident angle)/sine(refractive angle)

=(sin 36)/(sin 20) =1.719

http://answers.yahoo.com/question/index?qid=20090110063902AAkwJoh

And the next link is more info on it:
http://webphysics.davidson.edu/faculty/dmb/edibleopticalmaterials/find_n_background.htm