A point source emits sound equally in all directions in a non-abs… - Vidyadip

MCQ

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

✓
$9:4$
B
$2:3$
C
$3:2$
D
$4 : 9$

✓

Answer

Correct option: A.

$9:4$

a
(a) Intensity $ \propto \frac{1}{{{{({\rm{Distance}})}^2}}}$

==> $\frac{{{I_1}}}{{{I_2}}} = {\left( {\frac{{{d_2}}}{{{d_1}}}} \right)^2} = {\left( {\frac{3}{2}} \right)^2} = \frac{9}{4}$

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