Why does a pencil appear to be bent when placed in a beaker of water?

1. A pencil appears to be bent when placed in a beaker of water due to the refraction of light.
2. The ray of light from the tip of the pencil (A) travels from an optically denser medium (water) to an optically rarer medium (air).
3. The ray is refracted at the surface of the water and bends away from the normal.
4. When this ray reaches the eye of the viewer, it appears to come from a point A’.
5. Similarly, all points between AB appear to come from corresponding points between A’B.
6. Therefore, the pencil appears to be bent and shorter, when viewed from the top.