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Refraction of light in a pool

  1. Mar 31, 2007 #1
    1. The problem statement, all variables and given/known data
    At the shallow end of a swimming pool, the water is 70.0 cm deep. The diameter of the cone of the light emerging from the water into the air above, emitted by a light source 10.0 cm in diameter at the bottom of the pool and measured by an observer on the edge of the pool 2.50 m away, is
    a) 1.60 m
    b) 1.70 m
    c) 1.75 m
    d) 1.80 m

    2. Relevant equations

    3. The attempt at a solution
    I am really confused, can anybody help me? I don't know where to start.

  2. jcsd
  3. Apr 1, 2007 #2
    i don't sure the situation is clear. how tall is the observer?
  4. Apr 1, 2007 #3

    Doc Al

    User Avatar

    Staff: Mentor

    This is a critical angle problem. Draw a diagram of the light (at the bottom of the pool) being emitted at all angles. Figure out the maximum angle that will be refracted--anything greater will just be reflected by the water surface--and use that to calculate the diameter of the cone.
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