Q 11-14-015NEETJEE MainMedium
A string fixed at both ends vibrates in its third harmonic at $300$ Hz. The string is $90$ cm long. The speed of waves on it is
Answer: (C) $180$ m/s
Third harmonic: $L = \dfrac{3\lambda}{2} \Rightarrow \lambda = 0.6$ m. $v = f\lambda = 300 \times 0.6 = 180$ m/s.
Solution by Sreeraj P, M.Sc Physics