1. Not finding help here? Sign up for a free 30min 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!

Light- critical angle/refraction/reflection

  1. May 31, 2012 #1
    I am stuck on three questions :(
    Formulas: nsin(x)=n sin (x)
    sinx=n2/n1


    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:
    1sin(26)=xsin(19.3)
    x=1.326

    sinx=1.326/1
    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:
    1sin(58.4)=1.309sinx
    x=40.59213054
    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:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook