8. Reflection Of Light

Reflection is the the change in direction of the wavefront at an interface between two different media so that the wavefront returns back into the medium from which it originated. That means the reflection of light is the process of sending back the light rays which falls on the surface of an object. Bouncing back of light rays after hitting any surface is called reflection of light. Reflection can happen for a couple reasons. Reflection off metals happens because electrons in the metal happen to be able to match the frequency of the light, so it bounces off. It can also happens because of a change in refractive index. So when there is an interface between two mediums, you get reflection. This is why you see reflection off from the material that are normally transparent.

If the surface is smooth and shiny, the light will reflect at the same angle at which it hits the surface. This is called regular reflection and produces good images. But for rough surfaces, the rays incident at slightly different points on the surface are reflected in completely different directions, because the normal to a rough surface varies in direction very strongly from point to point on the surface. This type of reflection is called diffuse reflection and this enable us to see non-shiny objects.

Laws of Reflections

The laws of reflections governs the reflection of light rays off smooth conducting surfaces and there are three laws for the reflection of light. They are :-

>>>Plane Of Incidence
The incident ray, the reflected ray and the normal to the reflection surface at the point of the incidence are all lie on the same plane; while the incident ray is the beam of light that initially strikes the mirror and the reflected ray is the beam of light that bounces off the mirror after striking the mirror.

>>> The reflected ray and the incident ray are on the opposite sides of the normal.

>>> The angle of incidence (i) is equal to the angle of reflection (r) that means the angle which the incident ray makes to the normal in equal to the angle which the reflected ray makes to the same normal