A pipe open at both ensa has a fundamental frequency f in air. The pipe is dipped vertically in the water, so that half of it is in water, The fundamental frequency of the air column is now

A) $\frac{f}{2}$

B) $\frac{3f}{4}$

C) $2f$

D) $f$


Option D


The fundamental frequency  of open pipe 


  Now, after half-filled with water it becomes a closed pipe of length l/2

The fundamental frequency of this closed pipe.


                                   = $\frac{v}{2l}=f$