# Refractive index and speed of light

1. May 5, 2008

### 3instein

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

A slab of glass has a refractive index of 1.3. What will be the speed of light in this glass?

2. Relevant equations

3. The attempt at a solution

$$\frac{sin i}{sin r}=1.3$$

???

2. May 5, 2008

### Chi Meson

Wrong equation. If you knew what this equation was, youwould know that you cant use it. The "i" and "r" are referring to angles, and are any angles given?

Try the equation that defines the index of refraction, n .

3. Sep 14, 2008

### scivet

light speed in the media = c/n

4. Sep 14, 2008

### Redbelly98

Staff Emeritus
Welcome to Physics Forums scivet!

We try to give hints to people, rather than giving the answer, when it's a homework question.

But since the question is from last semester, no harm done!