Question

A cylindrical tube, open at both ends, has a fundamental frequency $f_o$in air. The tube is dipped vertically into water such that half of its length is inside water. The fundamental frequency of the air column now is

• A. 3f_o/4
• B. f_o
• C. f_o/2
• D. 2f_o

Answer 1

The correct option is B f_o

$n_{open}=\frac{v}{2l_{open}}$

$n_{closed}=\frac{v}{4l_{closed}}=\frac{v}{4l_{open}/2}=\frac{v}{2l_{open}}$

$(As{l}_{closed}=\frac{l_{open}}{2})$,i.e. frequency remains unchanged.