Q 11-14-113JEE MainJEE Main 2019 (10 Jan, Shift 2)Easy
A closed organ pipe has a fundamental frequency of $1.5\ \text{kHz}$. The number of overtones that can be distinctly heard by a person with this organ pipe will be (Assume that the highest frequency a person can hear is $20{,}000\ \text{Hz}$).
Answer: (C) $6$
A closed pipe gives only odd harmonics: $1.5, 4.5, 7.5, 10.5, 13.5, 16.5, 19.5\ \text{kHz}$ are all below $20\ \text{kHz}$ (the next, $22.5\ \text{kHz}$, is not).
That is 7 audible frequencies; leaving out the fundamental, there are $6$ overtones.
Solution by Sreeraj P, M.Sc Physics