Reflection of Light


Reflection of light is a phenomenon of bouncing back of light after hitting a surface.
When a ray of light falls on a surface some of the light reflects, some passes through the surface (refract) and some gets absorbed by the surface. As of now we are talking about reflection only.



When the surface is smooth like mirror or polished metal surface the kind of reflection takes place is called Specular Reflection. 2 things are to be noted here
  1. The incident ray, the reflected ray and the normal ( perpendicular ) to the surface lie on the same plane
  2. The angle of incidence and the angle of reflection are always equal

They are called laws of reflection of light.

But if the surface is not smooth like, wall or paper or screen the incident rays reflect in different directions and the light diffuse in the surrounding. This type of reflection is called Diffuse Reflection.



Mirror Vs Screen

In Mirror Specular Reflection takes place and the reflected ray of light move to a specific direction after reflection. The mirror (or the polished surface) can be rotate to direct the reflected rays. Remember when we used to play with a mirror and disturb people with sunlight on their face ??

In a screen, for example movie theatre screen, light is projected from a light source. Screen is a rough surface and thus causes Diffuse Reflection. The reflected light scatters in every direction. Thus the light ( or image made of the light ) can be seen from any angle.

Atmosphere and our indoor lighting are also results of diffuse reflection. Light from the sun or ( electrictric bulbs in indoor ) is reflected by the dust particles and the walls and we get a scattered light.


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