# Homework Help: Reflection, refraction

1. Mar 13, 2012

### kthejohnster

1. The problem statement, all variables and given/known data
A 45,45,90 glass triangular prism (n=1.52) is surrounded by air. If a light ray comes in to one of the legs (not hypotenuse) at a right angle which legs have total internal reflection?

2. Relevant equations

n_1sinx_i=n_2sinx_r

3. The attempt at a solution
i figured out that the light ray on the first incident leg transmits light to hypotenuse at but am getting confused on how to get the reflection angle at the hypotenuse to figure out how light hits the other leg

Edit: the light comes in at the arrow at a right angle. What happens to light at side b and c in the attached pic

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Last edited: Mar 13, 2012
2. Mar 14, 2012

### th4450

The angle of incidence i = 0o since the ray comes at right angle.

3. Mar 14, 2012

### Staff: Mentor

Consider the ray striking side c and emerging into air. Because air is a less dense medium, that ray as it emerges into air is angled further away from the normal than was the incident ray. Just how much further? https://www.physicsforums.com/images/icons/icon2.gif [Broken]Apply that formula you provided.

Last edited by a moderator: May 5, 2017