Why does the intensity of waves from a small source decrease with the square of the distance from the source?
A)The waves run out of energy as they travel.
B)The waves spread out as they travel.
C)The medium through which the waves travel absorbs the energy of the waves.
D)The waves slow down as they travel away from the source.
E)The frequency of the waves decreases as they get farther from the source.

Question

Quizplus · Accepted Answer

When waves from a small source travel through a medium, they spread out in a circular pattern. As they spread out, they cover a greater area so their intensity decreases. The intensity of the wave is inversely proportional to the square of the distance from the source. This is known as the inverse square law. It means that as the distance from the source doubles, the intensity of the wave drops to one-fourth of its original value.

Why Does the Intensity of Waves from a Small Source