Thank you for reporting, we will resolve it shortly
Q.
If the air column in a pipe which is closed at one end, is in resonance with a vibrating tuning fork at a frequency $260 \,Hz$, then the length of the air column is
Waves
Solution:
Frequency of the tuning fork, $v=260\, Hz$
The fundamental frequency of a closed organ pipe is $v=\frac{v}{4 L}$
where $v$ is the velocity of sound in air.
$\therefore \,\,\,$ Length of air column is $L=\frac{v}{4(v)}=\frac{330}{4 \times 260}=31.7\, cm$