Q 11-14-109JEE MainJEE Main 2020 (5 Sep, Shift 1)Medium
In a resonance tube experiment when the tube is filled with water up to a height of $17.0\ \text{cm}$ from bottom, it resonates with a given tuning fork. When the water level is raised the next resonance with the same tuning fork occurs at a height of $24.5\ \text{cm}$. If the velocity of sound in air is $330\ \text{m s}^{-1}$, the tuning fork frequency is:
Answer: (A) $2200\ \text{Hz}$
Successive resonances differ in air-column length by $\dfrac\lambda2$: $\dfrac\lambda2 = 24.5 - 17.0 = 7.5$ cm, so $\lambda = 15$ cm.
$$f = \frac{330}{0.15} = 2200\ \text{Hz}$$
Solution by Sreeraj P, M.Sc Physics