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Homework Help: How to prove Snell's law

  1. Jul 25, 2013 #1
    Can someone help me on how to prove Snell's Law using Fermat's principle? I'm not so good with topics about light, so I don't how to start.

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    Last edited: Jul 25, 2013
  2. jcsd
  3. Jul 25, 2013 #2


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    Staff: Mentor

    Looks like you've made a start...

    It also looks like you might want to write out expressions for sines of the relevant angles in terms of the variables you're using so that you'll be able to recognize them later. Then apply Fermat's principle to the time expression you've written. After that it'll be a lot of banging away at the algebra in order to pattern-match the sine expressions...

    Remember to express your velocities c1 and c2 in terms of the indexes of refraction.
  4. Jul 26, 2013 #3
    I got it! Thanks :)
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