A closed organ pipe and an open organ pipe of some length produce ` 2 beats ` when they are set up into vibration simultaneously in their fundamental mode . The length of the open organ pipe is now halved and of the closed organ pipe is doubled , the number of beats produced will be

Options

A. `8`
B. `4`
C. `7`
D. `2`

Answer

C

Explanation

`(n_(0))/(n_(c ))=2impliesn_(0)=2n_(c )` and `n_(0)-n_(c )=2`
`impliesn_(c )=2 ` and `n_(0)=4`
`n oo (1)/(l)impliesn._(0)=8` and `n._(c )=1`