Q 11-14-130JEE MainJEE Main 2019 (12 Apr, Shift 2)Easy
A tuning fork of frequency $480$ Hz is used in an experiment for measuring speed of sound $(v)$ in air by resonance tube method. Resonance is observed to occur at two successive lengths of the air column, $l_1 = 30$ cm and $l_2 = 70$ cm. Then, $v$ is equal to:
Answer: (A) $384\ \text{m s}^{-1}$
Successive resonances differ by $\lambda/2$: $\lambda = 2(70 - 30) = 80$ cm.
$$v = f\lambda = 480\times0.8 = 384\ \text{m/s}$$
Solution by Sreeraj P, M.Sc Physics