Please help!!Suppose a speaker is sending out a signal of a given power uniforml
ID: 1319220 • Letter: P
Question
Please help!!Suppose a speaker is sending out a signal of a given power uniformly in all directions. You are located a certain distance from the speaker measuring the intensity of the sound. Given the following different situations, rank the measured intensity (1 = the lowest intensity).
Power of speaker is 3P and distance to speaker is 3d.
Power of speaker is 9P and distance to speaker is (1/3)d.
Power of speaker is (1/9)P and distance to speaker is (1/3)d.
Power of speaker is 9P and distance to speaker is 3d.
Power of speaker is P and distance to speaker is d.
Explanation / Answer
The sound intensity decreases with distance to source. Intensity and distance can be expressed as:
I = Pi/4*?*r^2
where:
1) Pi = sound power (W)
2) ? = 3.14
3) r = radius or distance from source (m)
We have A) 3P/9d^2 = 1/2(P/d^2)
B) P/d^2
C) 9P/9d^2 = P/d^2
D) P/(9*9)d^2 = 1/81P/d^2
E)P/d^2
E) P/(4*d^2/4) = P/d^2