What is Reflection?

Reflection is the change in direction of a wave at a boundary between two different media so that the wave moves back into the medium it came from.

The most common examples include the reflection of light, & sound.

For example, Let’s see the reflection of light

When a ray of light falls on a smooth polished surface or mirror, the light rays bounce off the surface, making the angle of incidence equal to the angle of reflection which we know as the "Reflection of Light". 

The incident light ray which falls upon the surface is said to be reflected off the surface.

The ray that bounces back is called the reflected ray.

If a perpendicular were to be drawn on the reflecting surface, it would be called normal.

The figure below shows the reflection of an incident ray on a plane mirror.