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Homework Help: Angular Spread Of Blue and Red Light Through Plastic

  1. Oct 4, 2009 #1
    1. The problem statement, all variables and given/known data
    The index of refraction for blue light in plastic is 1.46 and for red light is 1.39. Determine the angular spread of the spectrum leaving the plastic block [presumably to air] for a beam of white light incident at angle of 45° to the plastic block.

    2. Relevant equations

    3. The attempt at a solution
    They are asking for white light, but I am only given blue and red?
    Using Snell's law to find:

    Blue - 1.46/1=sin45/sinX
    X= 28.97

    Red - 1.39/1=sin45/sinY

    Is that right? Would blue would leave at 28.97° and red at 31.33°. What about white light?

  2. jcsd
  3. Oct 4, 2009 #2


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    What wavelength is white light?
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