Reflection

Reflection takes place when incoming light strikes the surface of a medium, obstructing some wavelengths which bounce back into the medium from which they originated.

• Reflection takes place when light is neither absorbed by an opaque medium nor transmitted through a transparent medium.
• When light reflects off a surface, the angle of incidence of an incoming ray as it approaches the surface is equal to the angle of reflection.
• The three laws of reflection are as follows:
  • The incident ray, the reflected ray and the normal to a surface all lie on the same plane.
  • The angle of the incident ray is equal to the angle which the reflected ray makes with the normal.
  • The incident ray and the reflected ray appear on opposite sides of the normal.
• If a reflective surface is very smooth, the reflection is described as being specular or regular.
• Specular reflection occurs when light waves reflect off a smooth surface such as a mirror. The arrangement of the waves remains the same and an image of objects that the light has already encountered become visible to an observer.
• Diffuse reflection takes place when light reflects off a rough surface. In this case, scattering takes place and waves are reflected randomly in many different directions and so no image is produced.
• Reflection can take place regardless of the optical density of the medium through which the incident light is propagating or of the medium it bounces off.