A rectangular slab ABCD, of refractive index `n_1` , is immersed in water of refractive index `n_2(n_1 lt n_2)`. A ray of light is incident at the surface AB of the slab as shown in Fig. Find the maximum value of angle of incidence `alpha_(max)`, such that the ray comes out only from the other surface CD.

Options

A. `sin^(-1) [(n_(1))/(n_(2)) cos (sin^(-1) (n_(2))/(n_(1)))]`
B. `sin^(-1) [n_(1) cos (sin^(-1) (1)/(n_(2)))]`
C. `sin^(-1) ((n_(1))/(n_(2)))`
D. `sin^(-1)((n_(2))/(n_(1)))`

Answer

A