# When can internal reflection be used to find the index of refraction

Tags:
1. Sep 30, 2016

### Cocoleia

1. The problem statement, all variables and given/known data
I need to describe an experiment in which I would use internal reflection to determine the index of refraction of material
2. Relevant equations

Snell's law
3. The attempt at a solution
I understand the concept of internal reflection, such as the critical angle etc. I am just unsure of what kind of experiment could let me determine the index of refraction

Last edited by a moderator: Sep 30, 2016
2. Sep 30, 2016

### Staff: Mentor

Can you show us a diagram of the critical angle, and show us the equation you would use to calculate the angle for TIR?

3. Sep 30, 2016

### Staff: Mentor

And how is that angle dependent on the two indices of refraction of the two materials at the boundary?

4. Sep 30, 2016

### Cocoleia

Critical angle = inverse sin(nr/ni
Once we reach the critical angle we will have total internal reflection.

5. Sep 30, 2016

### Staff: Mentor

So if you know the index for the lower index material, and can control the angle of incidence into the boundary, you should be able to determine the unknown index experimentally, right?