1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Geometrical optics question.

  1. May 31, 2016 #1
    1. The problem statement, all variables and given/known data
    A container with a layer of water (n=1.33) of 5 cm thick is over a block of acrylic (n=1.5) of 3 cm thick. An observer watches (perpendicularly from above) the lowest surface of the acrylic. What distance does it (the bottom surface) seems to be from the top of the water?

    2. Relevant equations
    (n1/p) - (n2/q) = (n1-n2)/r

    3. The attempt at a solution
    (n1/p) - (n2/q) = 0

    q = n2p/n1
    Last edited: May 31, 2016
  2. jcsd
  3. Jun 1, 2016 #2
    i think you can use the relation ship between real depth of an abject and apparent depth of the same object related to ratio of the refractive indices of the medium.
    as the bottom is being viewed vertically so one can take paraxial rays close to the vertical and extend the emergent ray below to find the apparent position of the image.
    what will be depth of the acrylic slab when viewed from water?
    and what will be the depth of this image when viewed from above -the water surface?
  4. Jun 2, 2016 #3


    User Avatar
    Homework Helper

    I would rather suggest to use Snell's law and a ray diagram :wink:

    Draw such a diagram with rays from a point on the bottom surface of the block.
    These rays are refracted when they pass from the block into the water (ignore the glass)
    and again as they exit the water surface. These rays will then indicate where the virtual
    image of the point is located if you extend the rays backwards.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted