Types of Reflection

1. Regular Reflection of Light: The reflection of light from a smooth and plane surface is called regular reflection.

• All the incident rays are parallel to each other.
• The angles of incidence (i₁, i₂, i₃,...) for all the rays are equal to their corresponding angles of reflection (r₁, r₂, r₃,...).
• As a result, the reflected rays are also parallel to one another.
• For example: mirrors or still water surfaces reflect light in this regular manner.

In Figure (a):

• The blue rays (incident rays) strike the smooth surface.
• Since the surface is even, the reflected rays (red) emerge in parallel directions, maintaining the equality of angles:
  i₁ = i₂ = i₃ = r₁ = r₂ = r₃.

2. Irregular Reflection of Light: The reflection of light from a rough or uneven surface is called irregular reflection.

• The incident rays may be parallel, but due to the uneven surface, the angles of incidence (i₁, i₂, i₃,...) are not equal.
• As a result, the angles of reflection (r₁, r₂, r₃,...) also vary:
  i₁ ≠ i₂ ≠ i₃ and r₁ ≠ r₂ ≠ r₃.
• The reflected rays scatter in different directions and are not parallel to one another.
• For example:  walls, rough roads, or crumpled paper scatter light irregularly.

In Figure (b):

• The blue rays (incident rays) strike the rough surface at uneven points.
• Because of the irregularities, the angles of incidence differ for each ray, leading to reflected rays (red) spreading in various directions.

Reflection of light from a smooth and rough surface