Ray

In a diagram, a light ray is a way of tracing the motion of light, and what happens when it encounters different media.

  • The field of geometric optics uses the idea that light is made up of rays when describing and explaining what happens when it encounters different media.
  • Light rays are not real, they are a concept used to produce an idealised explanation of light.
  • Ray diagrams use straight lines and arrows to show how light propagates.
  • In the natural world light is not really made up of rays. More accurate descriptions of the properties of light use terms such as photons or waves.
  • So a light ray is a diagrammatic representation of a narrow beam of light travelling through a vacuum or medium.
  • The nearest thing to a light ray in the real world is a narrow focused beam of light produced by a laser.
Related diagrams

Each diagram below can be viewed on its own page with a full explanation.

References