When the distance between a point source of light and a light meter is reduced from 6.0 m to 2.0 m, the intensity of illumination at the meter will be the original value multiplied by:
A)3
B)9
C)1/3
D)1/9
E)1

Question

Quizplus · Accepted Answer

The intensity of illumination is inversely proportional to the square of the distance from the source.

In this case, the distance is reduced from 6.0 m to 2.0 m, which means the distance is decreased by a factor of 3 (6.0 / 2.0 = 3).

According to the inverse square law, if the distance is decreased by a factor of 3, the intensity will increase by a factor of (3)^2 = 9.

Therefore, the answer is B, 9.

When the Distance Between a Point Source of Light and a Light