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Homework Help: Variable index of refraction

  1. Oct 27, 2013 #1


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    1. The problem statement, all variables and given/known data
    A narrow beam of light passes through a slab obliquely and is then received by an eye. The index of refraction of the material in the slab fluctuates slowly with time. How will it appear to the eye?

    2. Relevant equations

    3. The attempt at a solution
    Let a point object be kept at a distance u to the left of the slab. Now I can find the final position of the image and it comes out to be (t/μ + 1) where t and μ are thickness and refractive index of the slab.
    Differentiating this wrt time
    dv/dt = c (dμ/dt)

    How to interpret this physically?
  2. jcsd
  3. Oct 27, 2013 #2


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    I'm not sure you are addressing the given problem. It says an oblique beam of light, not an object viewed perpendicularly through the slab. So I don't think distances come into it (but that might have been a more interesting question).
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