Q. A glass tube of length 1.0 m is completely filled with water. A vibrating tuning fork of frequency 500 Hz is kept over the mouth of the tube and water is drained out slowly at the bottom of tube. If velocity of sound in air is $330\ ms^{- 1}$, then the total number of resonance that occur will be
A) 2
B) 3
C) 1
D) 5
Explanation
(b) Frequency
$n = \frac{v}{4l}or\ l = \frac{v}{4v}$
$\therefore l_{1} = \frac{v}{4v_{1}} = \frac{300}{4 \times 500} = 0.165m;$
$l_{2} = \frac{3v}{4v_{1}} = 3\iota_{1} = 0.495\ m$
$l_{3} = \frac{5v}{4v_{1}} = 5\iota_{1} = 0.825m$
$and\ l_{4} = \frac{7v}{4v_{1}} = 7l_{1} = 1.155 > 1m$
Therefore, number of resonance =3
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.