# Homework Help: Angle of refraction through ice into water

1. Nov 10, 2008

### goWlfpack

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

A layer of ice having parallel sides floats on water. If light is incident on the upper surface of the ice at an angle of incidence of 15.0°, what is the angle of refraction in the water?

2. Relevant equations

3. The attempt at a solution
i know its not so simple that i can just use Sin theta n1 = sin theta n2.... but i dont know how the fact that it is parallel will change the equation. Should i find the angle of refraction in the ice and then use that as the angle of incidence for the water???

2. Nov 10, 2008

### mgb_phys

The equation only applies at a point on the surface - being parallel just means that you don't care where on the surface.

It's almost the same as the typical experiment with light going through a glass block.
You simply apply Snell's law ( n1 sin t1 = n2 sin t2 ) at each surface.
You will need the refractive index of ice and remember which way light bends at each surface.

3. Nov 10, 2008

### G01

Yup. That's how you should go about this problem. Use Snell's law twice, once at each interface.