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Homework Help: Need help with angle of incidence of light through a prism

  1. May 12, 2014 #1
    1. The problem statement, all variables and given/known data
    The direction of the ray of light enters equilateral 60° glass prism normal to the surface as shown in attached image
    refracted index of the prism material for the violet light is 1.651

    (a) What is the angle of incidence on the surface A-B?
    (b) Does total internal reflection occur?
    (c) Draw a ray diagram to show how light passes through
    the prism

    2. Relevant equations
    critical angle-----sin i c= 1/n

    3. The attempt at a solution
    My attempt
    a) critical angle
    sin= 1/1.651
    = 37.3°
    Not sure if its 90° for the incidence for side A-B

    b) Total internal reflections occur because the angle of incidence is greater
    then the critical angle

    c) i also attached my attempt to the image.

    thank you any help would be great

    Attached Files:

  2. jcsd
  3. May 12, 2014 #2
    The calculation seems correct, but the way you expressed it is confusing.
    You wrote
    "sin= 1/1.651
    = 37.3°"

    You should have written
    "sin θc= 1/1.651
    θc = 37.3°"
  4. May 12, 2014 #3
    thank you any chance you can tell me if my ray diagram in the picture attached is correct?
  5. May 12, 2014 #4


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    Homework Helper


    Note that the angle of incidence is defined as the angle the ray encloses with the normal of the surface.
    At totalreflecton, the ray is reflected from the surface AB inside the prism, and is incident onto an other side, and then leaves the prism.

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