Question

Sound waves from a tuning fork $F$ reach a point $P$ by two separate routes $FAP$ and $FBP$. $FBP$ is $12cm$ larger than $FAP$. There is silence at $P$. If the separation becomes $2cm$, the sound becomes maximum at $P$ and at $36cm$ there is again silence and so on. The least frequency of tuning fork is

• A. 1357 Hz
• B. 1735 Hz
• C. 1375 Hz
• D. 1400 Hz

Answer 1

Answer: (C)

1375 Hz

$\frac{\lambda }{2}=12cm$ or $\lambda =24cm$

$f=\frac{330}{0.24}=1375Hz$.