A ray is incident at an angle of incidence i on one surfcae of a small angle prism (with angle of prism A) and emerges normally from opposite surface. If refractive index of material of prism is `mu` then the angle of incidence is nearly equal to

Options

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

Answer

C

Explanation

Light ray emerges normally from another surface, hence e(angle of emergence) = 0
`r_(2) = 0 `
`r_(1) + r_(2) = A`
`rArr r_(1) = A `
Applying Snell’s law on first surface
1.sin i= `mu` sin `r_(1)`
`rArr " " sin i= mu sin A `
For small angles `(sin theta = theta ) `
Hence, i = `muA `.