Question

Refraction cannot cause bending as light moves from one surface to another if the incident and refracted angles i and r are related as
1) i not equal to r =0 degree
2) i = r = 90 degree
3) i = r = 0 degree
4) i = 90 degree r = 0 degree

Answer 1

The light ray will pass without refraction if it passes perpendicularly because then all the surfaces get their speeds reduced at the same time and there is no bending.
something like this



now the angle of incidence is the angle made by the incident ray with the normal.
as the normal and the incident ray coincide
there is no angle made

$angle \: i = 0$

and hence no refraction takes place

$angle \: r = 0$


so the correct answer is 3)

Answer 2

Answer:

3) i = r = 0 degree

Explanation:

angle of incidence is 0 and the ray is perpendicular to the refracting surface and coincident with the normal