- #1

shards5

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## Homework Statement

A spherical source radiates sound uniformly in all directions. At a distance of 9 m, the sound intensity level is 100 dB. What power is radiated by this source?

Just a simple answer check to see if my answer is reasonable.

## Homework Equations

[tex]\beta[/tex] = 10 db log (I/I

_{0})

Intensity = power/area

## The Attempt at a Solution

First convert the given decibels to Intensity then convert the found intensity to power via the second equation.

100 dB = 10 dB log (I/(1*10^-12)

Divide by 10 on both sides.

10 = log ((I/(1*10^-12)

Raise both sides to the tenth power to get rid of log

10

^{10}= (I/(1*10^-12))

Multiple both sides by 1*10

^{-12}I get. . .

I = 0.01 (Can someone confirm that I doesn't have units?)

Plugging in I to the second equation I get. . .

0.01 = [tex]\frac{Power}{4*\pi*9^2}[/tex]

Divide both sides by area I get Power. . .

Power = 10.178 (I know the units should be watt but if Intensity has no units and area only gives m

^{2}then how do I get the units for watt? Does this mean this is wrong?)

Thanks in advance for your help.