# Calculate the angle out

1. Apr 14, 2009

### shimizua

1. The problem statement, all variables and given/known data
Light is incident on an equilateral crown glass prism at a thetain = 43.5o angle to one face, as seen in the figure below.
Calculate the angle (thetaout) at which light emerges from the opposite face. Assume that n = 1.52.
2. Relevant equations
ok so i did snells law and found it to be 26.94 deg.
so i know also that a triangle is 180 deg so i should just be able to subtract it all and get the answer

3. The attempt at a solution
well i subtracted it and got 109.56 deg and it was wrong

2. Apr 14, 2009

### Kurdt

Staff Emeritus
work out the angle that it strikes the other face first and then apply Snell's law again.

3. Apr 14, 2009

### shimizua

i dont get what u mean by that?

4. Apr 14, 2009

### Kurdt

Staff Emeritus
The beam of light is refracted on the other surface of the prism, correct? What is the incident angle for that surface? Then you can work out the angle it leaves the prism.