Question

A long glass tube is held vertically in the water. A tuning fork is struck and held over the tube. Strong resonances are observed at two successive lengths $0.50m$ and $0.84m$ above the surface of the water. If the velocity of sound is $340m/s$, then the frequency of the tuning fork is (neglect end corrections)

• A. $128Hz$
• B. $256Hz$
• C. $384Hz$
• D. $500Hz$

Answer 1

The correct option is D $500Hz$

For given data:

The velocity of the sound $=340m/s$

Resonance observed at two successive lengths $l_1=0.50m$ and $l_2=0.84m$.

$\Rightarrow \frac{\lambda }{2}=(l_2-l_1)=(0.84-0.5)m=0.34m$

$\Rightarrow \lambda =0.34\times 2m=0.68m$

To find; Frequency of tunning fork

We know the formula

Frequency, $f=\frac{v}{\lambda }$

$=\frac{340}{0.68}$

$f=500Hz$

Frequency of tuning fork is $500Hz$