Q. What is meant by refraction?
A. The bending of a ray of light, as it passes from one medium to another.
Q. How is a ray of light bent, as it passes from one medium to another?
A. When a ray of light passes into a denser medium, it is bent towards the perpendicular. When it passes into a rarer medium, it is bent from the perpendicular.
Suppose DE to be a perpendicular line.
If AB (a ray of light,) enters the water, it will be bent towards the perpendicular to C.
If (on the other hand) CB (a ray of light) emerges from the water, it would be bent away from the perpendicular towards A.
Q. Why does a spoon (in a glass of water) always appear bent?
A. Because as the light of the spoon emerges from the water, it is refracted.
And the spoon looks like ABC. (See the last figure.)