A ray of light is incident at an angle `alpha` on the boundary separating two transparant media. It transmited in other medium. If the angle incidence is increased very slightly, the ray gets reflected in the same medium. The different between angles of deviation in the two cases will close to

Options

A. `alpha`
B. `90^(@)-alpha`
C. `180^(@)-alpha`
D. `180^(@)-2alpha`

Answer

B

Explanation

When the ray is incident at the critical angle `alpha`, the angle of deviation is `(90^(@)-alpha)` wheras just after this (that angle is at an angle slightly greater than the critical angle) the angle of deviation is `(180^(@)-2alpha)`.