Equations of progressive wave is given by
`y=4 sin [pi(t/5-x/9)+ pi /6]` Then , which of the following is correct ?

Options

A. `v=5 m//s`
B. `lambda =18 m`
C. `A=0.04 m`
D. `f = 50 Hz`

Answer

B

Explanation

`lambda = (2pi)/(k) = (2pi)/((pi)//(9)) = 18 m`