Question

A uniform tube of length 60 cm stands vertically with its lower end dipping into water. First two air column lengths above water are 15 cm and 45 cm, when the tube responds to a vibrating fork of frequency 500 Hz. Find the lowest frequency (in Hz) to which the tube will respond when it is open at both ends.

Answer 1

When pipe is dip in water it will act s closed at one side.

So, $500=\frac{v}{4l}$ at $l=15cm$

$500=\frac{3v}{4l}$ at $l=45cm$

So, $v=300m/s$

Now, when open at both ends,

$f=\frac{v}{2l}=\frac{300}{2\times 60\times {10}^{-2}}=250Hz$