# Refractive Indexes

## Homework Statement

A beam of light from a laser in a vacuum has a wavelength of 632.8nm and is incident on the surface of a glass slab. In the vacuum the beam make an angle of 32degrees witht the normal to the surface, while in the glass is makes an angle of 21.0degrees with the normal.

a)what is the index of refraction of the glass?

b)what is the wavelength of light in the glass?

## Homework Equations

snell's law

wavelength1/wavelength2=n1/n2

## The Attempt at a Solution

i know the wavelength is 632.8 so i tried subbing them into snells law and got
632.8sin32=n2sin21
but the answer i got couldn't be right, its 243 and this could be the refractive index.

hellppp!!!!!

ehild
Homework Helper
Check what is Snell's law exactly.

ehild

snell's law= n1sinangle1=n2singangle2

ehild
Homework Helper
It is OK, but 632.8 nm is wavelength, not refractive index. What is the refractive index of vacuum?

ehild

the only other information i have is the speed of light in vacuum which is 3x10^8

ehild
Homework Helper
And how is the refractive index defined?

ehild

when vi=c do you make it
sinangle=nsinangle and solve for n?

ehild
Homework Helper
yes.

ehild

sin32=nsin21 just writing it here so i remember when i come back

ehild
Homework Helper
sin32=nsin21 just writing it here so i remember when i come back

Yes, evaluate.

ehild

yep, thanks!