Question

Does the intensity of light from a lamp vary inversely, directly or neitheras the square of the distance on sits from it?

Answer 1

Light intensity varies inversely as the surface area of the sphere with the light source at the sphere's center.

Since the surface area of a sphere varies as the square of the radius:
`color(white)("XXXXX")` `A_("surface") = 4pi r^2`

Therefore the intensity of light varies inversely as the square of the distance from the light source (i.e. the radius).