In a diagram, a light ray is a way of tracing the motion of light, including its direction of travel, and what happens when absorption, dispersion, polarization, reflection, refraction, scattering or transmission take place.

  • A light ray is a component of a geometric model (a ray diagram) of the properties of light.
  • Whilst the world in general terms literally appear before our eyes, many of the properties of the electromagnetic spectrumare invisible to us.
  • Simplified models are used to explore and explain some of the invisible optical phenomena. Ray diagrams represent light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces.
  • So a light ray is a diagrammatic representation of a narrow beam of light travelling through a vacuum or medium.
  • Light waves are part of a similar model (wave diagram). Wave diagrams imagine light to be a wave, with peaks and troughs and allow other properties to be shown that a ray does not make evident.
  • Light can also be described in terms of photons which allows additional properties to be modelled.
  • One of the conventions used to represent photons is a  Feynman diagram.