Angular spread of light rays passing through a prism

[Quenton Robertson]

Homework Statement

The problem asks:
The index of refraction for violet light in silica flint glass is 1.66, and the index of refraction for red light is 1.62. What is the angular spread of visible light passing through a prism of apex angle 60 degrees if the angle of incidence is 50.03 degrees?

Homework Equations

n1=1.62
n2=1.66
n =1
theta1=50.03
Angular spread= arcsin[n*sin(theta1)/n1] - arcsin[n*sin(theta1)/n2]

The Attempt at a Solution

I plugged in my numbers into the equation above and got:

Angular spread= arcsin[1*sin(50.03)/1.62] - arcsin[1*sin(50.03)/1.66]

and got: 0.7388

but that was wrong...so where did I go wrong?

 

[BvU]

0.7388 radians seems a bit much... Maybe you mean degrees ? Is that for the entrance into the glass only ?

 

[Quenton Robertson]

0.7388 radians seems a bit much... Maybe you mean degrees ? Is that for the entrance into the glass only ?

yeah sorry, i meant degrees :P the question wants the answers in degrees too
is the 60 degree number important? if so where do i use it?

 

[BvU]

You might use it on the other side of the prism to calculate the angle of incidence there...

Thing to do: make a drawing indicating the various angles...

 

[Quenton Robertson]

Could you show me what you mean by that?

 

[Ibix]

Is that for the entrance into the glass only ?

@Quenton Robertson - this is, I think, the key point.

 

[BvU]

Maybe QR missed my second line in #4 (I first posted a one-liner )