# SS: Reflection of light

Show/Hide Sub-topics (Reflection And Refraction Of Light | O Level)

Reflection of light is the abrupt change in the direction of propagation of light rays that strike the boundary between different mediums. Terms used:

A ray of light is light from a single point source (normally represented by a long and straight arrow on diagrams.

Incident ray is a ray of light striking a surface.

Reflected ray is a ray of light reflected from a surface.

Normal is an imaginary line perpendicular to a surface where the reflection occurs.

Angle of incidence (i) is the angle between the incident ray and the normal.

Angle of reflection (r) is the angle between reflected ray and the normal.

Laws of reflection

First law:

The incident ray, the reflected ray and the normal to the surface all lie in the same plane.

Second law:

The angle of incidence is equal to the angle of reflection. ### Regular Reflection

• Regular reflection refers to the reflection of rays coming from a smooth plane surface.
• All incident rays have parallel reflected rays

### Diffused (irregular) reflection

• Refers to the reflection of rays coming from rough surfaces
• The reflected rays are not in the same direction
• However, at each point on the rough surface, the laws of reflections are obeyed. 