A sound consists of four frequencies : `300 Hz , 600 Hz,1200 Hz and 2400 Hz`. A sound 'filter' is made by passing this sound through a bifurcate pipe as shown . The sound wave has to travel a distance of `50 cm` more in the right branch - pipe than in the straight pipe. The speed of sound in air is `300 m//s`. Then , which of the following frequencies will be almost completely muffled or 'silenced' at the outlet?

Options

A. `300 Hz`
B. `600 Hz`
C. `1200 Hz`
D. `2400 Hz`

Answer

A

Explanation

For minima ,
`Delta x = ( 2n + 1) (lambda)/(2)` and `lambda = (v)/(f)`
`0.5 = (( 2n + 1))/(2) (300)/(f)`
`f = ( 2 n + 1) 300`
Therefore , all odd multiples of `300` are silenced.