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

$A$ 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

$A$ travelling wave is partly reflected and partly transmitted from a rigid boundary. Let $a_i, a_r$ and $a_t$ be the amplitudes of the incident wave,reflected wave,and transmitted wave,and $I_i, I_r$ and $I_t$ be the corresponding intensities. Choose the correct alternative.

If the separation between the screen and the source is increased by $2\%$,what would be the effect on the intensity?

$A$ person speaking normally produces a sound intensity of $40 \ dB$ at a distance of $1 \ m$. If the threshold intensity for reasonable audibility is $20 \ dB$,the maximum distance at which he can be heard clearly is ... $m$.