Question

A ray of light is incident at small angle I on the surface of prism of small angle A and emerges normally from the oppsite surface. If the refractive index of the material of the prism is mu, the angle of incidence is nearly equal to
A. `A/mu`
B. `A/(2mu)`
C. `muA`
D. `(muA)/(2)`

Answer 1

Correct Answer - C
As refracted ray emerges normally from opposite surface, `r_(2) = 0`
As `A = r_(1) + r_(2) :. r_(1) = A`
Now, `mu = (sini_(1))/(sinr_(1)) = (i_(1))/(r_(1)) = (i)/(A)` or `I = muA`