# Angles of Light and Prisms

1. Aug 5, 2014

### StumpedFrosh

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

Light is incident on a glass prism with an angle of incidence of 54°. The light enters on the left hand side of a triangular prism with base angles of 80° and apex angle of 20°. (The 54° ray of incidence enters from the south west side of the prism, directed towards the north east). Calculate all the angles as a ray of light travels through a prism. Assume that the prism is surrounded with air therefore n=1, also the n value of the prism is n=1.7.

2. Relevant equations

snell's law: n1sinΘ1=n2sinΘ2

3. The attempt at a solution
With the given information i drew the image and determined through snell's law that the first angle of refraction (Θ2) equals 28.4°... I don't understand how to find Θ3.

2. Aug 5, 2014

### Simon Bridge

You have to use you knowledge of triangles and angles to work out an incident angle to the second side.
Since you have a sketch, you can continue the ray into the prism until it strikes the other side.
The ray and the apex of the prism will make a triangle where you know two of the angles.