The intensity of sound after passing through a slab decreases by $30\%$. On passing through two such slabs,the intensity will decrease by ..... $\%$

The intensity of sound from a radio at a distance of $2 \ m$ from its speaker is $1 \times 10^{-2} \ \mu W/m^2$. The intensity at a distance of $10 \ m$ would be:

$A$ 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

The intensity ratio of two waves is $1 : 16$. The ratio of their amplitudes is

If the ratio of intensities of two waves is $1 : 25$,then the ratio of their amplitudes will be

$A$ 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 . . . . . . $\times 10^{-8} \text{ W m}^{-2}$.