Polaroid sunglasses reduce glare because reflected light from a horizontal surface is

  • A. partially polarised in the horizontal plane, which the filter blocks
  • B. of a different frequency
  • C. travelling faster
  • D. already absorbed by the surface

Explanation

Reflection off water or a road partially polarises the light horizontally, so a filter oriented to transmit only vertical vibrations removes most of the glare while passing ordinary light. This works only because light is a transverse wave. Rotating the glasses through 90 degrees makes the glare reappear, which is a simple demonstration of the effect.

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