Three sound waves of equal amplitudes have frequencies `(v -1), v, (v +1)`. They superpose to give beats. The number of beats produced per second will be

Options

A. `2`
B. `1`
C. `4`
D. `3`

Answer

B

Explanation

`sin2pint + sin 2pi(n - 1)t + sin 2pi (n + 1) t`
`sin 2pint + 2 sin '([2pit(n - 1 + n + 1)])/(2)"cos"([2pit(n + 1 - n + 1)])/(2)`
`sin2pint + 2 sin 2pint cos 2pit`
`sin2pint[1 + 2 cos2pit]`
`rArr f_("beat") = 1`