A tuning fork of frequency 480 Hz is used in an experiment for measuring speed of sound $(v)$ in air

Question

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, $l_{1}=30 \mathrm{~cm}$ and $l_{2}=70 \mathrm{~cm}$. Then $v$ is equal to\

Professor PC Thomas Classes · Answer

(a) : Given, frequency of tuning fork, $v=480 \mathrm{~Hz}$\ Resonance lengths, $l_{1}=30 \mathrm{~cm}$ and $l_{2}=70 \mathrm{~cm}$\ Speed of sound $(v)_{	ext {air }}=2 v\left(l_{2}-l_{1}ight)$\ $=2 	imes 480 	imes 40 	imes 10^{-2}$\ $=38400 	imes 10^{-2} \mathrm{~m} \mathrm{~s}^{-1}=384 \mathrm{~m} \mathrm{~s}^{-1}$\