1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Snell's Law x2: Double-checking trig?

  1. Aug 1, 2007 #1


    User Avatar

    1. The problem statement, all variables and given/known data

    In this drawing:

    http://img245.imageshack.us/img245/6559/physgv8.png [Broken]

    Index of refraction for glass: 1.52
    Index of refraction for surrounding carbon disulfide: 1.63
    Incident angle at point A: 43.0°
    At what angle does the ray leave the glass at point B?

    2. Relevant equations

    [tex]n_{1}sin\theta_{1} = n_{2}sin\theta_{2}[/tex] (twice)

    3. The attempt at a solution

    Please double-check my conceptual understanding of this.

    Part 1, as light travels through the carbon disulfide into the glass:

    [tex]1.63sin43 = 1.52sin\theta_{2}[/tex]

    [tex]\theta_{2} = sin^{-1}\frac{1.63sin43}{1.52}[/tex]

    So Θ within the glass is 47°.

    Drawn out and making a triangle with the upper left hand corner of the glass, a triangle forms with point B as one of its own points, meaning that the angle with a normal line at that point would be 180 - (90 + 47) = 43°.

    Part 2, as light travels through the glass back into the carbon disulfide:

    [tex]1.52sin43 = 1.63sin\theta_{2}[/tex]

    [tex]\theta_{2} = sin^{-1}\frac{1.52sin43}{1.63}[/tex]

    Which yields 39.4923°.

    Am I going about this correctly?
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Aug 1, 2007 #2


    User Avatar
    Homework Helper

    Looks OK to me.
  4. Aug 1, 2007 #3


    User Avatar

    Thanks for taking a peek - turned out to be correct.
  5. Aug 1, 2007 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Looks correct to me too.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook