Question

If fundamental frequency of closed pipe is $50Hz$, then frequency of second overtone is:

• A. 100 Hz
• B. 50 Hz
• C. 250 Hz
• D. 150 Hz

Answer 1

Answer: (C)

A closed pipe produces only odd harmonics i.e., $1:3:5:7$.

If $v$ is the velocity of sound in air, $n$ is the frequency of note emitted and $l$ is the length of pipe then
$n=\frac{v}{4l}$
Also a closed pipe produces only odd harmonics i.e., $1:3:5:7\dots \dots \dots$
Hence, second overtone or fifth harmonic frequency is
$=\frac{5v}{4l}=5\times 50=250Hz$