Hello aspirant
To retrace its path light rays should fall normally on the reflecting surface. So,
r2=0
r1=A−r2⇒r1=A
Now applying snell rule between incident ray and refracted ray.
(1) sin (2A) = n sin A
2sinAcosA=nsinA
Therefore, n=2cosA
I.e The refractive index μ, of the prism is 2cosA.
Hope this helps
Question : The _______ of a ray is the angle measured from the reflected ray to the normal surface.
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