Question

A tuning fork of frequency $480\, Hz$ is used in an experiment for measuring speed of sound (n) 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 :

• A. $332\, ms^{-1}$
• B. $379 \,ms^{-1}$
• C. $384\, ms^{-1}$
• D. $338\, ms^{-1}$

Answer 1

Answer: (C)

$384\, ms^{-1}$

Answer 2

$v = 2f(l_2 - l_1)$
$v = 2 \times 480 \times (70 - 30) \times 10^{-2}$
$v = 960 \times 40 \times 10^{-2}$
$v = 38400 \times 10^{-2} m/s$
$v = 384 \, m/s$