# Homework Help: Light Refraction

1. Nov 5, 2009

### JDiorio

1. The problem statement, all variables and given/known data
An underwater swimmer observes that a beam of sunlight in the water makes an angle of 18.7° with the vertical. The index of refraction for water is equal to 1.33. Assuming the surface of the water is level, determine the beam's angle as it enters the water.

2. Relevant equations

n1sin(theta1)=n2sin(theta2)

3. The attempt at a solution

I tried using different angles but I cant seem to get the correct answer. At first I used 18.7 degrees and found that to be incorrect. Than I thought that 18.7 might not correspond since it is made with the vertical and not the horizontal, so I used 90-18.7= 71.3 degrees but that didnt work either. I am not sure if I am using the wrong equation or if I am misreading the question.

2. Nov 5, 2009

### JDiorio

Nevermind I found my mistake. I didn't realize the 18.7 degree angle was after it already was in the water. Thanks anyway.