The wave velocity of progressive wave is 480 m/s and the phase difference between the two particles separated by a distance of 12 m is `1080^(@)`. Then the number of waves passing across a point in 1 s is

Options

A. 120
B. 60
C. 240
D. 360

Answer

A

Explanation

`delta = (1080pi)/(180) = 6pi`
`delta = (2pi x)/(lamda) " " :. lamda = (2pi x)/(delta)`
`lamda = (2pi xx 12)/(6pi) = 4m`
`n = (v)/(lamda) = (480)/(4) = 120 Hz`