# Light rays passing through a glass prism

## Homework Statement:

Prism is placed as shown. AC is coated with a silver film which acts as a mirror. A light beam is an incident onto prism at Point Q such that angle PQB is 40 degrees. Refracted light is reflected by the mirror along the incident path. What is the refractive index of the prism?

## Relevant Equations:

##n_{1}\sin \theta _{1}=n_{2}\sin \theta _{2}## Hi all!
Breaking down the question bit by bit:
AC is coated with a silver film which acts as a mirror - Okay, nothing as of yet right..?
A light beam is an incident onto prism at Point Q such that angle PQB is 40 degrees - This means that my incident angle is 50 degrees as shown below.
Refracted light is reflected by the mirror along the incident path - I know there is something to this, but what does it exactly imply?

Seeing that I only can make sense of the second statement, I proceeded to draw the diagram: Should if the part where I arrowed out is 90 degrees, will the equation be as such:
##n_{1}\sin \theta _{1}=n_{2}\sin \theta _{2}##
##1*sin50=nsin30##
And n will be the refractive index?
Thanks.

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mjc123
Homework Helper
Refracted light is reflected by the mirror along the incident path - I know there is something to this, but what does it exactly imply?
The incident beam strikes AC at an angle of 90°.
Should if the part where I arrowed out is 90 degrees, will the equation be as such:
n1sinθ1=n2sinθ2
1∗sin50=nsin30
And n will be the refractive index?
Yes
(NB: 360 - 75 -75 -90 ≠ 60, but it didn't stop you getting it right.)

• jisbon and berkeman
The incident beam strikes AC at an angle of 90°.

Yes
(NB: 360 - 75 -75 -90 ≠ 60, but it didn't stop you getting it right.)
Oh yep I wrote it wrongly. But thanks for clarifying my concepts 