# Homework Help: Index of refraction and speed of light

1. Jan 10, 2012

### Yusufzai

Had this question in a test today, :).
1. The problem statement, all variables and given/known data

Carbon tetrachloride (n = 1.46) is poured into a container made of crown glass (n = 1.52). What's the speed of light in the liquad?

2. Relevant equations
v=c/n

3. The attempt at a solution

I just multiplied 1.46 by the speed of light. I wanted to know if this is the correct way to do it, what confused me the most was the 2 index of refraction.

2. Jan 10, 2012

### Sebastian H

To get the speed, you just divide c by n = 1.46. Using the formula you gave correctly yourself. If you multiply c with a number bigger then 1, you'd get a speed greater then that in vacuum.

I can't see why you're given the n value for the crown glass material, since the speed in the liquid wouldn't depend on it. Are you sure there wasn't any questions about the refraction angle, or such, where both refractive indexes are used?

3. Jan 10, 2012

### mrkrgn

v= c/n
c is the speed of light
v is the speed in the new medium