Question

A resonance of diameter $2cm$ is vibrating in unison with a tuning fork of frequency $512Hz$. When the length of air column above water level is $13.5cm$, the wavelength of the note will be

• A. $31.0cm$
• B. $32.2cm$
• C. $54cm$
• D. $62.0cm$

Answer 1

The correct option is C $54cm$

When the air column is filled with water, the resonant length is the length above the water level and is

$l=(2n+1)\frac{\lambda }{4}$
where, $\lambda$ is the wavelength of waves inside the column.
Hence, for $n=0,$ the length will be

$l=\frac{\lambda }{4}$

$\lambda =4l$

$\lambda =4\left(13.5\right)=54cm$.