Calculate the minimum angle of incidence so that a ray travelling from glass `(mu = 3//2)` to water `(mu = 4//3)` does not emerge out in water.

Explanation

Here, `._(g)mu^(a) = (3)/(2), ._(w)mu^(a) = (4)/(3) , i_(min) = C = ?`
`:. ._(g) mu^(w) = (._(g)mu^(a))/(._(w)mu^(a)) = (3//2)/(4//3) = (9)/(8)`
As `sin C = (1)/(._(g)mu^(w)) = (1)/(9//8) = (8)/(9) = 0.8888`
`C = sin^(-1) (0.8888) = 62.7^(@)`.