A guitar has a power output of 0.25 W. If the sound waves emitted by the guitar travel in spherical wavefronts, what will be the intensity of the sound at a distance of 4 m?

Question

anonymous · Answer

http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/invsqs.html That should give you a nicer explaination than I'd be able to write out on the spot, but feel free to ask if you have any other questions!

anonymous · Answer

umm please write @LifeEngineer

anonymous · Answer

hmm?

anonymous · Answer

okay ill show you my work sorry for being lazy

anonymous · Answer

4*pi*2^2=50.26
0.25/50.26=4.9*10^-3

anonymous · Answer

@LifeEngineer

anonymous · Answer

Close! The distance from the source is 4m, not 2m, so you would end up with:
$$I = \frac{ 0.25 }{ 4\pi 4^2 }$$

anonymous · Answer

That will give you an answer in watts per square meter. If you need an answer in decibels, then you can convert fairly easily using $$I(dB)=10\log( \frac{I}{I_o})$$

anonymous · Answer

hint: if you scroll down on the link I gave you, there is also a calculator for this type of problem, after it gives the explanation of how everything works