Q 11-14-016NEETJEE MainTop questionMedium
Two successive resonant frequencies of a string fixed at both ends are $420$ Hz and $490$ Hz. Its fundamental frequency is
Answer: (D) $70$ Hz
For a string fixed at both ends, $f_n = nf_1$, so successive harmonics differ by $f_1 = 490 - 420 = 70$ Hz. (They are the $6^{\text{th}}$ and $7^{\text{th}}$ harmonics.)
Solution by Sreeraj P, M.Sc Physics