# Homework Help: Question about refraction of light

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

### rl.bhat

Use Snell's Law. It gives the relation between the refractive index of incident medium, sine angle of incidence, refractive index of the refracted medium and sine of the angle of refraction in the refracted medium.

3. 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

4. Oct 5, 2009

### rl.bhat

The light is going from acetone to air. So it should be
sin(30)/sin(42) = 1/n2