Question

In the experiment of repraction through a glass slap,
angle of
incidence
should be less than 90°. Why?​

Answer 1

Answer:

The angle of incidence is nearly equal to the angle of emergence. The angle of refraction is less than angle of incidence because light is travelling from rarer to denser optical medium.

Answer 2

Answer:

if it 90 degree then that would passes through the normal, Then there would be no refraction takes place. In order to get refraction, Anglesey must be less than 90 °