The sound signal is sent through a composite tube as shown in the figure. The radius of the semicircular portion of the tube is $r$. Speed of sound in air is $v$. The source of sound is capable of giving varied frequencies in the range of $v_1$ and $v_2$ (where $v_2>v_1$). If $n$ is an integer then frequency for maximum intensity is given by

  

Two identical tubes $A$ and $B$ are kept in air and water, respectively, as shown. If the fundamental frequency of $A$ is $f_0$, then the fundamental frequency of $B$ is

A tube of diameter d and of length $l$ unit is open at both ends. Its fundamental frequency of resonance is found to be ${\nu }_1$. The velocity of sound in air is $330 \mathrm{m} {\mathrm{s}}^{-1}$. One end of the tube is now closed. The lowest frequency of resonance of tube is now ${\nu }_2$. Taking into consideration the end correction $\frac{{\nu }_2}{{\nu }_1}$ is