Two tuning forks $P$ and $Q$ are vibrated together. The numbers of beats produced are represented by the…
Two tuning forks $P$ and $Q$ are vibrated together. The numbers of beats produced are represented by the straight line $OA$ in the following graph. After loading $Q$ with wax, again these are vibrated together and the beats produced are represented by the line $OB$. If the frequency of $P$ is 341 Hz, the frequency of $Q$ will be
341 Hz
338 Hz
344 Hz
None of these
Solution
$n_Q = 341 \pm 3 = 344\text{ Hz}$ or $338\text{ Hz}$
On waxing $Q$, the number of beats decreases, hence
$n_Q = 344\text{ Hz}$.