Due to refraction, the apparent depth of water in a pond appears less than the real depth. Because of the phenomenon of refraction, light rays coming from the bottom of the pond bend when they reach the surface. As a result, it appears to be coming from a different position above the actual depth of the pond.

Following are the laws of refraction of light:

1. The normal ray, incident ray and refracted ray, all lie on the same plane.
2. The ratio of sine of angle of incidence to the angle of refraction is always constant for a given pair of media, i.e., mu = (sin i / sin r).
3. When a ray of light passes from denser to rarer medium (DAR), it goes away from normal. When a ray of light passes from rarer to denser medium, it goes towards the normal. A ray of light incident normally passing without refraction.

The refractive index of a glass is 1.5. This means that the velocity of light is 1.5 times slower in glass as compared to the velocity of light in air/vacuum.