A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is

Options

A. `45^(@)`
B. `39^(@)`
C. `20^(@)`
D. `30^(@)`

Answer

D

Explanation

`i=e=(3)/(4)A`
Where i is the angle of incidence, e is the angle of emergence and A is the angle of prism.
As, `A+delta=i+e`
`:.delta=i+e-A=(3)/(4)A+(3)/(4)A-A=(A)/(2)=(60^(@))/(2)=30^(@)`