An air column in a resonace tube of length `1.5` m resonates with a source of frequency 125 Hz, when the water level in it at a certain height from the bottom of the tube. What is the height of water level corresponding to the fundamental frequency ?
( Neglect the end correction and speed of sound in air is 330 m/s)`

Options

A. `1.2` m
B. `0.5` m
C. `0.84` m
D. `0.42` m

Answer

C

Explanation

Let L be the resonating length for the fundamental frequency (f) . `f = v/(4l) `
`:. L = v/(4f) :. L = 330/(4 xx 125) = 0.66` m
` :. ` Height of water column ` = 1.5 - 0.66 = 0.84` m