A ray of light suffers a minimum deviation when incident on a equilateral prism of refractive index `sqrt2` . The angle of incidence is

Options

A. `30^(@)`
B. `45^(@)`
C. `60^(@)`
D. `50^(@)`

Answer

B

Explanation

`n=(sin((A+D)/(2)))/(sin((A)/(2)))`
`sqrt(2)=((sin(60+D))/(2))/(sin""(60)/(2))`
`sqrt(2)=(sin((60+D)/(2)))/(sin30)`
`sqrt(2)xx(1)/(2)=sin((60+D)/(2))`
`=(60+D)/(2)=45`.
`60+D=90`
`D=30`
`2i=A+D`
`2i=60+30`
`i=(90)/(2)`
`i=45^(@)`