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Homework Help: Index of refraction for violet light

  1. Apr 6, 2009 #1
    1. The problem statement, all variables and given/known data
    The index of refraction for violet light in silica flint glass is 1.65 and for red light is 1.62.What is the angle of deviation for the red ray passing through a prism of apex angle 59.7 degrees. If the angle of incidence is 47.4 degrees.

    2. Relevant equations

    nglass sine theta3 = nredlight sine theta4
    nredlight sine theta1 = nglass sine theta2

    Angle of deviation = [theta 1 + theta 4 ] - apex angle

    3. The attempt at a solution
    I know the equations to be used. but I dont understand the figure that accompanies this problem in the textbook. Can someone post a general picture, with all of these angles labeled and provide a starting thrust?

    Thank you!
  2. jcsd
  3. Apr 6, 2009 #2


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    Homework Helper

    Re: prism

    I'd suggest that you make your own drawing, putting in the angles. The initial rays will coincide, but they will diverge on their way to the next internal surface. Use Snell's law to determine the first angles and that gives you the internal angles of incidence for the next surface (you know the apex angle) and then Snell's Law again should give you the external exit angle shouldn't it?
  4. Apr 13, 2009 #3
    Re: prism

    so for my answer i got 48.7 which was correct. Now i need to find the angle of dispersion of visible light with the same angle of incidence . So i found the angle of deviation for the violet light which was 52.27. then i subtracted the two to get the anglular dispersion which came out to be 3.57. but this is not correct. Please help
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