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

Answer

A

Explanation

`because e = 0 `,
`therefore " " r_(2) = 0 , " and " r_(1) ` = A
`n_(1) sin i= n_(2) sin r_(1)`
as `n_(1) = 1 " and " n_(2) = n`
`therefore ` for small angle i= nA
`rArr ` i= `muA `