(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A concert loudspeaker suspended high off the ground emits 28.0W of sound power. A small microphone with a 0.900cm^2 area is 51.0m from the speaker.

A) What is I at the microphone?

B) How much sound energy impinges on the microphone in J?

2. Relevant equations

I = P/A

I = 4pir^2

3. The attempt at a solution

I have solved the answer to part A):

I = 28W/4pi(51)^2 = 8.57*10^-4 W/m^2

The answer to part B is what's eluding me:

I know that at the microphone I = 8.57*10^-4 W/m^2

So:

8.57*10^-4 = P/.009m^2

P = 7.713*10^-6 W which is equal to J/s

Therefore my answer would be 7.713*10^-6 J of sound energy are impinged each second.

Mastering Physics is disagreeing with me. Any advice?

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# Homework Help: Sound intensity at a microphone

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