Snell's Law, indices of refraction

[monke]

Homework Statement

A beam of light in air is incident on a stack of 4 flat transparent materials with indicies of refraction 1.20, 1.40, 1.32, and 1.28. If the angle of incidence for the beam on the first of the four materials is 60*, what angle does the beam make witht the normal when it emerges into the air after passing through the entire stack?

Homework Equations

what is the best way to start and understand this type of problem?

The Attempt at a Solution

Do I just use Snell"s Law and use the incides of refraction of air for n sub i and 60 for theta sub i?

Thanks in advance :)

 

[technician]

A good exercise in this question is to use this version of snell's law:
n1Sinθ1 = n2Sinθ2 and apply this as you work through each layer.
You will get an answer that may surprise you.
Once you get this answer it will reveal something about light entering and leaving parallel sided blocks.

 

[monke]

okay what do i use for the n1 sinθ1? is that 60* and the n for air =1.000?

 

[monke]

then do i just add all the thetas together?

 

[monke]

oh i think i got it you use n=1.00 sin60= 1.20sin theta 1 and then solve for theta 1 and sub in all down the layers until you use n=1.00 and solve for theta i. the angle is the same going out of the layers as it was going in?

 

[technician]

That is it.
If the block has parallel sides the light emerges at the same angle it entered.

 

[technician]

That is it.
If the block has parallel sides the light emerges at the same angle it entered.