An empty vessel is partially filled with water. What happens to the frequency of vibration of the air column in the vessel?

The frequency of a vibrating air column in a pipe,open at both ends,is $f_1$. When $\frac{3}{4}$ of its length is immersed in water,the frequency of the vibrating air column is $f_2$. The value of $\frac{f_1}{f_2}$ is

The fundamental frequency of an open pipe is $100 \ Hz$. If the bottom end of the pipe is closed and $1/3$ rd of the pipe is filled with water,then the fundamental frequency of the pipe is: (in $Hz$)

The fifth overtone of an open pipe of length $L_0$ is in unison with the fifth overtone of a pipe closed at one end of length $L_c$. The ratio of $L_0$ to $L_c$ is:

Sound waves of frequency $600 \,Hz$ fall normally on a perfectly reflecting wall. The shortest distance from the wall at which all particles will have maximum amplitude of vibration is (speed of sound $= 300 \,ms^{-1}$)

Two closed organ pipes,when sounded simultaneously,give $4$ beats per second. If the longer pipe has a length of $1 \ m$,then the length of the shorter pipe will be,... $cm$ $(v = 300 \ m/s)$.