A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at a distance of 2 m and 3 m respectively from the source. The ratio of the intensities of the wa

Question

A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at a distance of 2 m and 3 m respectively from the source. The ratio of the intensities of the waves at P and Q is

TestHub · Accepted Answer

The average power per unit area that is incident perpendicular to the direction of propagation is called the intensity, i.e.,

$I = \frac{P}{4 {πr}^{2}}$

$I \propto \frac{I}{r^{2}}$

$\frac{I_{2}}{I_{2}} = {(\frac{r_{2}}{r_{1}})}^{2}$

Here, $r_{1} = 2 m, r_{2} = 3 m$

$∴ \frac{I_{1}}{I_{2}} = {(\frac{3}{2})}^{2} = \frac{9}{4}$

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