A ray of light passes from a medium X to another medium Y. No refraction of light occurs if the ray of light hits the boundary of medium Y at an angle of:

When a ray of light travelling in glass enters into water obliquely:

A ray of light travelling in water falls at right angles to the boundary of a parallel-sided glass block. The ray of light:

Which of the following diagrams shows the ray of light refracted correctly?

A vertical ray of light strikes the horizontal surface of some water:

(a) What is the angle of incidence?

(b) What is the angle of refraction?