A source of frequency 340 Hz is kept above a vertical cylindrical tube closed at lower end. The length of the tube is 120 cm. Water is slowly poured in just enough to produce resonance. Then, the minimum height (velocity of sound = 340 m/s) of the water level in the tube for that resonance is

Options

A. 0.75m
B. 0.25m
C. 0.95m
D. 0.45m

Answer

D

Explanation

`f_(s)=340 Hz`
`L=120 cm`
`l_(1) = (v)/(4f)`
`=(340)/(4xx 340)`
`=(1)/(4)=0.25=25 cm`
`h=l_(2)-3l_(1)`
`l_(2)=120 cm`
`h=120 - 3xx 25`
`h=120-75`
`=45 cm =0.45 m`