Question

Why the angle of refraction is less than angle of incidence when a ray of light passes
obliquely from air to glass slab?

Answer 1

Because glass slab have more optical dencity than air hence light ray will bend towared normal and angle of incidence will be greater than angle of refraction.

Hope this is helpful.

Answer 2

Explanation:

In the normal case scenario, the refracted light comes from a rare medium to a denser medium. The angle of refraction or r is more than angle of incidence or i. We know that water is optically denser than air , when the light enter into air, then it would bend .It basically happens cause the speed of light will decrease when it travels from air into glass or water.