Homework Help: Question about light refraction

1. Oct 5, 2009

kevinf

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

n=c/v

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. Oct 5, 2009

3. Oct 5, 2009

kevinf

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?

4. Oct 5, 2009

gnurf

You will find your answer by googling index of refraction for air.

5. Oct 5, 2009

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.

6. Oct 5, 2009

kevinf

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

7. Oct 5, 2009

sin42/sin30.This gives the refractive index of acetone from air.

8. Oct 5, 2009

kevinf

so sin(42)/sin(30) = n2/1? so it should be about 1.34 right?

9. Oct 5, 2009