# Quick Question about Refraction and Light

1. Oct 7, 2008

### sethie2000

Quick Question about Refraction and Light!!

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

http://www.webassign.net/hrw/hrw7_33-55.gif

Suppose a prism has apex angle ϕ = 62.0° and index of refraction n = 1.58. What is the smallest angle of incidence θ for which a ray can enter the left face of the prism and exit the right face?

2. Relevant equations
Snell's Law - - n1sin(x1) = n2sin(x2)
Critical Angle -- sin(xc) = n2/n1

3. The attempt at a solution
I figured out the critical angle at exit from the right side (39.27). I'm just confused about what the angle (x2) would become in the Snell's Law equation. Would it be 180-39.27?

Could someone let me know if what I did was incorrect so far, or how to find the angle x2 for the Snell's Law equation. Thanks!

2. Oct 7, 2008

### nasu

Re: Quick Question about Refraction and Light!!

The angle between the two normals is equal to the angle of the prism.
Look at the triangle formed between the two normals and the light ray inside the prism.
This will give you the angle x2.
Good luck

3. Oct 7, 2008

### sethie2000

Re: Quick Question about Refraction and Light!!

I got the correct answer. Thanks for the help nasu!