A ray of light passing through a prism having refractive index `sqrt2` suffers minimum deviation. It is found that the angle of incidence is double the angle of refraction within the prism. What is the angle of prism?

Explanation

`mu=sqrt2`, `i=2r`

`1xxsini=musinr`
`sin2r=musinr`
`2sinrcosr=musinr`
`cosr=mu/2=sqrt2/2=1/sqrt2=cos45^@`
`r=45^@`
When `delta=delta_m`, `r=A/2`
`A=2r=90^@`