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: Question about light refraction

  1. Oct 5, 2009 #1
    1. The problem statement, all variables and given/known data

    A pair of students measure the refraction of light in passing from acetone into air for several angles. When the angle of incidence is 30, the angle of refraction is 42.
    (a) What is the index of refraction n of the acetone?

    2. Relevant equations


    3. The attempt at a solution

    i am not sure if there is another way to calculate the index of refraction. i can't find v (speed of light in acetone) so i don't think the provided equation will work. is there another way to calculate it? i also searched up google for index of refraction for acetone and it gave me 1.36 but even that's not correct. any ideas?
  2. jcsd
  3. Oct 5, 2009 #2
    You will find your answer by googling Snells law
  4. Oct 5, 2009 #3
    ok so snelll's law says sim(theta1) /sin(theta2) = n2/n1. wouldn't i still need to know the index of refraction for air? or is that a constant that is usually given?
  5. Oct 5, 2009 #4
    You will find your answer by googling index of refraction for air.
  6. Oct 5, 2009 #5
    The refractive index of vacuum is 1 and the refractive index of air is slightly higher,the difference,however, is so very small that we take the refractive index of air as being 1.
  7. Oct 5, 2009 #6
    so just to make sure it would be sin(30)/sin(42) = n2/1? i just want to make sure since this is my last try
  8. Oct 5, 2009 #7
    sin42/sin30.This gives the refractive index of acetone from air.
  9. Oct 5, 2009 #8
    so sin(42)/sin(30) = n2/1? so it should be about 1.34 right?
  10. Oct 5, 2009 #9
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook