List of top Physics Questions on Waves asked in Haryana PMT

The limbs of a U-tube are vertical and have internal diameters $0.5 \,cm$ and $1 \,cm$ respectively. If the tube contains water, what will be the difference in the surface level in the limbs? (Surface tension of water $= 72$ dyne/cm)

The fundamental frequency of a closed pipe is $220 \,Hz$. If $\frac{1}{4}$ of the pipe is filled with water, the frequency of the first overtone of the pipe now is