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Snell's Law, indices of refraction

  1. Mar 20, 2012 #1
    1. The problem statement, all variables and given/known data

    A beam of light in air is incident on a stack of 4 flat transparent materials with indicies of refraction 1.20, 1.40, 1.32, and 1.28. If the angle of incidence for the beam on the first of the four materials is 60*, what angle does the beam make witht the normal when it emerges in to the air after passing through the entire stack?

    2. Relevant equations

    what is the best way to start and understand this type of problem?

    3. The attempt at a solution

    Do I just use Snell"s Law and use the incides of refraction of air for n sub i and 60 for theta sub i?

    Thanks in advance :)
     
  2. jcsd
  3. Mar 20, 2012 #2
    A good exercise in this question is to use this version of snell's law:
    n1Sinθ1 = n2Sinθ2 and apply this as you work through each layer.
    You will get an answer that may surprise you.
    Once you get this answer it will reveal something about light entering and leaving parallel sided blocks.
     
    Last edited: Mar 20, 2012
  4. Mar 20, 2012 #3
    okay what do i use for the n1 sinθ1? is that 60* and the n for air =1.000?
     
  5. Mar 20, 2012 #4
    then do i just add all the thetas together?
     
  6. Mar 20, 2012 #5
    oh i think i got it you use n=1.00 sin60= 1.20sin theta 1 and then solve for theta 1 and sub in all down the layers until you use n=1.00 and solve for theta i. the angle is the same going out of the layers as it was going in?
     
  7. Mar 21, 2012 #6
    That is it.
    If the block has parallel sides the light emerges at the same angle it entered.
     
  8. Mar 21, 2012 #7
    That is it.
    If the block has parallel sides the light emerges at the same angle it entered.
     
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