Describe an experiment to show that a light ray bends when it passes from one transparent medium into another transparent medium.

Define incident ray, refracted ray, angle of incidence and angle of refraction.

Explain why a coin placed at the bottom of a vessel appears to be raised when water is poured in the vessel.

Explain why a straight stick partly dipped in water obliquely, appears to be bent at the surface of the water.

Explain why the sun is seen before the sunrise and after the sunset.