A ray of light travelling in the direction `(1)/(2)``(hati+sqrt3hatj)` is incident on a plane mirror. After reflection, it travels along the direction `(1)/(2)` `(hati-sqrt3hatj)` . The angle of incidence is

Options

A. (a)`30^(@)`
B. (b)`45^(@)`
C. (c)`60^(@)`
D. (d)`75^(@)`

Answer

A

Explanation

Here normal is along `hatj`
Angle between incident ray and normal
`"cos"theta = ((1)/(2) (hati + sqrt(3hatj)). Hatj)/((1)(1)) = (sqrt(3))/(2) implies theta = 30^(@)`