A prism is made from a piece of glass with a triangular cross-section. The angle

Question

A prism is made from a piece of glass with a triangular cross-section. The angles of the triangle are 90, 45, and 45. As shown schematically in the figure below, the beam of light enters the glass perpendicular to the long side of the triangle, and is then internally reflected off the back wall of the prism, and again totally internally reflected from the bottom wall of the prism, before re-emerging from the long side of the prism.

a. Determine the angle between the incoming and the outgoing light beams.

b. If the prism is surrounded by air (n=1), what is the minimum index of refraction of the glass for the total internal refraction to happen?

Explanation / Answer

Consider this Traingle ABC, Angle A be the 45egrees and B be 90degrees and C is 45 degrees

From the figure we can consider AB =BC and angle A =Angle C, at each reflcetion angle i =45degrees = C (critical angle)

Theerefore the minimum value of refractive for the total internal reflcetion is u =1/sinC =1/sin45 =1/(1/Sqrt(2) =SQRT(2) =1.414

Here the light ray incident normally with an angle of 90degrees then with same angle it will come out.

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