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

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

$A$ point source emits sound equally in all directions in a non-absorbing medium. Two points $P$ and $Q$ are at a distance of $9 \ m$ and $25 \ m$ respectively from the source. The ratio of the amplitudes of the waves at $P$ and $Q$ is

$A$ string of mass $100 \, g$ is clamped between two rigid supports. $A$ wave of amplitude $2 \, mm$ is generated in the string. If the angular frequency of the wave is $5000 \, rad/s$,then the total energy of the wave in the string is ..... $J$.

If the ratio of the amplitude of two waves is $4 : 3$,then the ratio of their maximum and minimum intensity will be:

$A$ is singing a note and at the same time $B$ is singing a note with exactly one-eighth the frequency of the note of $A$. If the energies of the two sounds are equal,the amplitude of the note of $B$ is: