Sound of wave length λ passes through a Quinke's tube and it produces sound of maximum intensity `I_(0)` Through what distacne should the sliding tube be moved to give an intensity `(I_(0))/(2)` ?

Options

A. `(lamda)/(2)`
B. `(lamda)/(3)`
C. `(lamda)/(4)`
D. `(lamda)/(8)`

Answer

D

Explanation

`I _(n ew) =I +I +2sqrt(II)cos phi=((I_(0))/(2))`
`2I (1+ cosphi) =(4I)/(2)`
`(1+ cos phi) =1`
`cos phi =0, phi=(pi)/(2)`
Path difference `=(lamda)/(4)`
Tube will have to be moved through distance `(lamda)/(8)`