Question

In the arrangement given below , there are two rectangular glass slabs placed side by side as shown . A ray of light is incident from air onto the surface of the glass slab 1 having refractive index n1 at an angle of incidence i . Thereafter , it moves through glass slab 2 of refractive index n2 and after emerging from the glass slab 2 , it reflects from a smooth horizontal plane mirror . The angle theta which reflected ray makes with the mirror is

Answer 1

So for angles of incidence greater than 48.6-degrees, TIR occurs. But 48.6 degrees is the critical angle only for the water-air boundary. The actual value of the critical angle is dependent upon the two materials on either side of the boundary. For the crown glass-air boundary, the critical angle is 41.1 degrees.