Question

A resonating air column shows resonance with a turning fork of frequency $256Hz$ at column lengths $33.4cm$ and $101.8cm$. The speed in air is:

• A. $300m{s}^{-1}$
• B. $250m{s}^{-1}$
• C. $390m{s}^{-1}$
• D. $350m{s}^{-1}$

Answer 1

The correct option is D $350m{s}^{-1}$

Given,

$L_1=33.4cm$

$L_2=101.8cm$

$f=256Hz$

The speed in air is given by

$v=2f(L_2-L_1)$

$v=2\times 256(101.8-33.4)cm/s$

$v=512\times 0.684$

$v=350m{s}^{-1}$

The correct option is D.