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Homework Help: Light- critical angle/refraction/reflection

  1. May 31, 2012 #1
    I am stuck on three questions :(
    Formulas: nsin(x)=n sin (x)

    1. A ray of light traveling in air strikes the surface of a liquid. If the angle of incidence is 26.0◦ and the angle of refraction is 19.3◦, find the critical angle for light traveling from the liquid back into the air.
    This is my work so far:

    I then get an error. I do not know what I'm doing wrong :(

    2. A ray of light traveling in air strikes the surface of a block of clear ice (n = 1.309) at an
    angle of 58.4◦ with the normal. Part of the light is reflected and part is refracted. Find the angle between the reflected and the refracted light.
    Work so far:
    I believe that this is the refracted angle, but what is the reflected angle/how do I find it?

    3. A submarine is 316 m horizontally out from the shore and 120 m beneath the surface of
    the water. A laser beam is sent from the submarine so that it strikes the surface of the
    water at a point 223 m m from the shore. If the beam strikes the top of a building
    standing directly at the water’s edge, find the height of the building. The index of refraction of water is 1.333.
    Answer in units of m
    Work so far: None, because I can't even comprehend it.

    Thanks for your help in advance :)
  2. jcsd
  3. May 31, 2012 #2
    I figured out 1 and 3, can someone help me with number two though?
  4. Jun 1, 2012 #3
    Great! :approve:

    So for (2),

    What is the relation between angle of incidence and reflection for any plain mirror? :wink:
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