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Homework Help: Optical Path Length

  1. Aug 9, 2004 #1
    This is the question:
    The optical path length of a light beam is nd where n is the refractive index and d is the physical distance. A light beam passes through 2.0 in thick glass (n=1.525) and then through 12 in. of water (n=1.33) and finally though 0.6 in of polystyrene (n=1.590). What is the optical path length?

    Is this too easy to just multiply the refractive index by the length and then add all of those numbers? When I did that I got about 20 inches. I was also wondering if I missed a trick or anything in this problem. The length could be different (instead of using the values of 2 in, 12 in, and 0.6 in) because the light becomes bent (with the refractive index). Does this set up a triangle in the glass, water, and polystrene? Is only the one side of the triangle 2 in and i am looking for the hypotenuse as a length value? If so how would i calculate that with no angles (or only a 90 degree one)?
    Thanks for reading.
  2. jcsd
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