When wave enters from one medium to the other medium, it changes its direction depending upon the angle of incidence because of the change in speed.
When wave enters from denser medium to the rare medium, it bends away from the normal. Its speed and wavelength increases but frequency remains same.
When wave enters from rare medium to the denser medium, it bends towards the normal. Its speed and wavelength decreases but frequency remains same.
Direction of refracted wave depends upon the direction of incident wave.
Law of refraction:
When wave refracts, its obeys the law of refraction which is as under.
1- Sine of angle of incidence is directly proportional to the sine of angle of refraction.
2- Incident wave, refracted wave and normal all they lie in the same plane.
Important to note:
1- Angle of incidence is the angle between incident wave and the normal to the boundary of the first medium at the point of incidence.
2- Angle of refraction is the angle between the refracted wave and the normal to the boundary of the second medium at the point of incidence, in which wave enters.
3- In refraction phenomenon, direction, wavelength and speed changes but frequency remains same.
4- In refraction phenomenon, if angle of incidence is zero (means wave is coming along the normal) then angle of refraction will also be zero and the wave goes straight in the second medium without bending, but speed and wavelength change depending upon the nature of the second medium in which it is entering.
5- In this syllabus we study three media: glass, water and air. Glass is most dense medium, then water and and water is denser than air. In water we study two regions shallow and deeper, deeper is the rare medium as compare to the shallow region.