Light- a form of energy, detectable with the eye, which can be transmitted from one place to another at finite velocity.

Visible light is a small portion of a continuous spectrum of radiation ranging from cosmic rays to radio waves.

Light spectrum

White or visible light, that which the eye detects, is only a fraction of the complete spectrum - produced by shining white light through a glass prism.

Two complimentary theories have been proposed to explain how light behaves and the form by which it travels.

  1. Particle theory - release of a small amount of energy as a photon when an atom is excited.
  2. Wave theory - radiant energy travels as a wave from one point to another.

Waves have electrical and magnetic properties => electromagnetic variations.

Wave theory effectively describes the phenomena of polarization, reflection, refraction and interference, which form the basis for optical mineralogy.

Components of a Light Ray