Question

Sound signal is sent through a composite tube as shown in figure. The radius of the semicircle is r. Speed of sound in air is V. The source of sound is capable to generate frequencies in the range $f_1$ to $f_2$ $(f_2>f)$. If 'n' is an integer then frequency for maximum intensity is given by :

• A. $\frac{nV}{r}$
• B. $\frac{nV}{r(\pi -2)}$
• C. ${7V}^{}/r$
• D. $\frac{nV}{(r-2)\pi }$

Answer 1

The correct option is B $\frac{nV}{r(\pi -2)}$

For it to be in synchronization,

$\pi r-2r=n\lambda$ $=\frac{nV}{f}$

$\Rightarrow f=\frac{nV}{r(\pi -2)}$