Consider ten identical sources of sound,all emitting the same frequency but having random phase angles. If the average intensity of each source is $I_0$,what will be the average resultant intensity $I$ due to all these ten sources?

As a wave propagates:

$A$ point source is emitting sound waves of intensity $16 \times 10^{-8} \text{ W m}^{-2}$ at a distance of $1 \text{ m}$ from the source. The difference in intensity (magnitude only) at two points located at distances of $2 \text{ m}$ and $4 \text{ m}$ from the source respectively will be . . . . . . $\times 10^{-8} \text{ W m}^{-2}$.

$A$ stone thrown into still water creates a circular wave pattern moving radially outwards. If $r$ is the distance measured from the centre of the pattern, the amplitude of the wave varies as

If the amplitude of waves at a distance $r$ from a point source is $A$,the amplitude at a distance $2r$ will be

The sound intensity level at a point $4 \,m$ from the point source is $10 \,dB$. Then the sound level at a distance $2 \,m$ from the same source will be ........ $dB$.