Meaning of inverse square law

in'verse square' law"

Pronunciation: [key]
— Physics, Optics. Physics,Optics.
  1. one of several laws relating two quantities such that one quantity varies inversely as the square of the other, as the law that the illumination produced on a screen by a point source varies inversely as the square of the distance of the screen from the source.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.