"The intensity of illumination on a surface from a source of light varies-inversely as the square
Channel: Doubtnut
Date: 2020-04-05

"The intensity of illumination on a
 surface from a source of light varies-inversely as the square of the distance
 of the surface from the source. The effect of moving a piece of paper 3 times
 as far from the source is to 
multiply
 the intensity by 3 
divide
 the intensity by 3 
multiply
 the intensity by 9 
divide
 the intensity by 9"