A wave has double the amplitude of a second wave. The energy density of the second wave is
A) four times that of the first wave.
B) double that of the first wave.
C) equal to that of the first wave.
D) half that of the first wave.
E) one-quarter that of the first wave.

Question

Quizplus · Accepted Answer

The energy density of a wave is proportional to the square of its amplitude. Therefore, if the amplitude of the first wave is double that of the second, its energy density will be $2^2 = 4$ times greater, making the energy density of the second wave one-quarter that of the first.

A Wave Has Double the Amplitude of a Second Wave