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Homework Help: Applications of refractive light

  1. Jan 29, 2010 #1
    1. The problem statement, all variables and given/known data

    b) White light travels from crown glass into ethanol. If the angle of incidence in crown
    glass is 60.00 degrees (not sure how to insert degree sign), what is the angular spread
    between the red and violet parts of the visible spectrum in the ethanol? Illustrate your
    answer with a light-ray diagram.

    2. Relevant equations

    Sini = 60o
    ni (for red light in crown glass) = 1.520
    nr (for violet light in crown glass) = 1.376
    nR (Ethanol) = 1.36

    (ni)(Sini) = (nR)(SinR)

    3. The attempt at a solution

    For red light:

    (ni)(Sini) = (nR)(SinR)
    (1.52)(Sin60) = (1.36)(SinR)
    SinR = (1.52)(0.866)/1.36
    SinR= 0.968

    I'm not sure if this is right but, if it is, I'm confused at how to get the angle on my caculator.

    Can someone let me know if i'm on the right track?

  2. jcsd
  3. Jan 29, 2010 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Yes, that's correct.

    Your calculator should have a button for inverse sine. On my calculator it's labeled sin-1. Make sure you are in degree mode or you might end up with an answer in radians. For example: sin-1(.5) = 30°
  4. Feb 1, 2010 #3
    when i hit the Sin-1 button it comes up asin(... so I type in asin(0.968) and hit enter. it comes up: 1.32

    why can't i get the degree? when i type in .5 (as in your example) the answer is 0.52

    what gives?
  5. Feb 1, 2010 #4
    never mind...got it
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