Electromagnetic waves

The form and composition of rainbows are often explained in terms of electromagnetic waves.

EM-Wave

Electromagnetic waves consist of coupled oscillating electric and magnetic fields orientated at 900 to one another. (Credit: https://creativecommons.org/licenses/by-sa/4.0)

  • Electromagnetic waves can be imagined as oscillating electric (E) and magnetic (B) fields arranged at right angles to each other.
  • In the diagram above, the coupled electric and magnetic fields follow the y-axis and z-axis and propagate along the x-axis.
  • This arrangement is known as a transverse wave which means the oscillations are perpendicular to the direction of travel.
  • By convention, the electric field is shown in diagrams aligned with the vertical plane and the magnetic field with the horizontal plane.
  • In normal atmospheric conditions the geometric orientation of the coupled y-axis and z axis is random, so the coupled fields EB may be rotated to any angle.