Determine the value of the angle of incidence for a ray of light travelling from a medium of refractive index `mu_1 = sqrt(2)` into the medium of refractive index `mu_2 = 1`, so that it just grazes along the surface of separation.

Explanation

Here, `mu_1 = sqrt(2) , mu_2 = 1`
If `i` is the angle of incidence of ray `Ko`, it would just graze along `OA`, as shown in (Fig. 11( c).15), when it suffers total internal reflection at `O`. This would happen when `/_i= C`, the critical angle for the pair of media in contact.
`sin C = (1)/(mu_1//mu_2) = (mu_2)/(mu_1) = (1)/(sqrt(2))`
`C = 45^@ = /_ i`.