A ray is ihncident at an angle of incidence ii on one surface of a prism of small angle A and emerge normally from opposite surface. If the refractive index of the material of prism is `mu.` the angel of incidance I is nearly equal to

Options

A. `-(A)/(mu)`
B. `(A)/(2mu)`
C. `muA`
D. `(muA)/(2)`

Answer

C

Explanation

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