Practice!

Sample Problem

If a spherical speaker uses 260W of power to make sound waves, what is the intensity of a sound wave 3.2 meters from the speaker?

Solution

We use the equation I = P/ (4πr2) . We know that P = 260W, that r = 3.2m, and we plug the values in to get I = 260/ (4π (3.2) 2) = 2.0kg/s3