# At what angle does the light leave the glass

## Homework Statement

The drawing shows a rectangular block of glass (n = 1.52) surrounded by a liquid with n = 1.79. A ray of light is incident on the glass at point A with a 30.0° angle of incidence. At what angle does the ray leave the glass at point B?

http://edugen.wiley.com/edugen/courses/crs1507/art/qb/qu/c26/ch26p_18.gif

## Homework Equations

n1*sin(theta1)=n2*sin(theta2)

## The Attempt at a Solution

I solved this and got the right answer by doing the steps below, however I have no idea why I put 1 in the denominater, and this is not the correct way to solve it because my friend's problem is not working out. Please help me figure out the proper way to solve this, as I've tried everything I can think of!

sin(theta2) = (1.6 sin30)/1 = 53.13 degrees

tiny-tim
Homework Helper
Hi phys62! sin(theta2) = (1.6 sin30)/1 = 53.13 degrees

Where did 1.6 come from? Show us your full calculations, and then we'll know how to help. Doc Al
Mentor
You need to apply Snell's law twice: Once at A; once at B. And you need to relate the angle of refraction at A to the angle of incidence at B.