Light is a form of visible electromagnetic radiation. It is a self-sustaining regular oscillation of electric and magnetic fields (perpendicular to each other), moving through space.

Light has a wave-particle duality - it has properties of both a wave and a particle.


  • Amplitude/Intensity: The distance/displacement between the crest of a wave and the centre of wave.
  • Frequency/Period (v): The number of waves passing a point per second. Period is 1/Frequency.
  • Wavelength: Distance between two adjacent crests
  • Velocity: Dependent on the density of the substance passing through.
  • Polarisation: The orientation of the oscillation

Light can be monochromatic or polychromatic (one wavelength vs multiple - e.g. sun = poly)