Light leaving a point source spreads out so that the apparent brightness I of light per unit area varies with distance d according to which law ( means "proportional to")?
A) I = constant
B) I 1/d²
C) I d²
D) I 1/d

Question

Light leaving a point source spreads out so that the apparent brightness I of light per unit area varies with distance d according to which law (  means "proportional to")?
A) I = constant 
B) I 1/d² 
C) I d² 
D) I 1/d

Quizplus · Accepted Answer

This is known as the inverse square law, which states that the brightness of light is inversely proportional to the square of the distance from the source. As the distance d increases, the apparent brightness I decreases rapidly.

Light Leaving a Point Source Spreads Out So That the Apparent