A tuning fork of frequency 340Hz vibrated above a cylindrical hallow tube closed at one end. The height of the tube is 120cm . Water is slowly poured in it. What is the minimum height of water required for resonance ?

Options

A. 95cm
B. 25cm
C. 45cm
D. 105cm

Answer

C

Explanation

`l_1 = (v)/(4n) = (340)/(4xx340) = 25cm`
`l_2=(3v)/(4n) = 3xx0.025 = 75cm`
`l_3=5l_1 = 5xx0.25 = 125cm`
The height of the tube is 120cm , the maximum height of the air column for resonance is 75 cm so the minimum height of the water is
120-75=45cm.