At a distance of 20 m from a sound source the intensity level is 60 dB.What is the intensity level (in dB)at a point 2.0 m from the source? Assume that the source radiates equally in all directions.
A)80 dB
B)45 dB
C)62 dB
D)87 dB
E)95 dB

Question

Quizplus · Accepted Answer

Intensity level is proportional to the inverse square of the distance from the source. So, if the distance is reduced to 1/10, the intensity level increases by a factor of (10)^2 = 100. Therefore, the intensity level at 2.0 m from the source is 60 + 40 (log 20/2) = 80 dB.

At a Distance of 20 M from a Sound Source