Polarization of electromagnetic waves refers to the geometrical orientation of their oscillations.

Polarization restricts the orientation of the oscillations of the electric field of electromagnetic waves to a single plane from the point of view of an observer. This phenomenon is known as plane polarization.

  • Plane polarization filters out all the waves where the electric field is not orientated with the plane from the point of view of an observer.
  • To visualize plane polarization, imagine trying to push a large sheet of card through a window fitted with close-fitting vertical bars.
  • Only by aligning the card with the slots between the bars can it pass through. Align the card at any other angle and its path is blocked.
  • Now substitute the alignment of the electric field of an electromagnetic wave for the sheet of card, and plane polarization for the bars on the window.
  • Polarizing lenses used in sunglasses rely on plane polarization. The polarizing plane is orientated horizontally and cuts out glare by blocking vertically aligned waves.
  • Plane polarization is one of the optical effects that account for the appearance of rainbows.
  • It is the position of each raindrop on the arc of a rainbow, with respect to the observer, that determines the angle of the polarizing plane.
  • Rainbows are typically 96% polarized.