Question

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.

Answer 1

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. when it suffers total internal reflection at `O`. This would happen when `angle 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^(@)`