Adjoining figureshows the snapshot of two waves A and B at any time t. the equation for A is y=Asin (kx-omegat-phi),and for B it is y=A sin (kx-omega t). It is clearly shown in the figure that wave A is ahead of B by a distance phi//k.

Adjoining figureshows the snapshot of two waves A and B at any time t.

1.	Adjoining figureshows the snapshot of two waves A and B at any time t. the equation for A is y=Asin (kx-omegat-phi),and for B it is y=A sin (kx-omega t). It is clearly shown in the figure that wave A is ahead of B by a distance phi//k.
Answer» Solution :The equation for wave A can be rewritten as `y=A sin[kx-omegat-phi]` `=A sin[k(X-phi//k)-omegat]` `A sin[kx-omega(t+(phi)/(k))]` while equation of wave `B` is `y= A sin (kx-omegat)`. Comparing above equation, we can easily conclude that `A` is at a distance ahead of `phi//k` from `B` or wave `A` is ahead of `B` by a TIME DIFFERENCE of `phi//omega`.So, (b) is the correct option. Remember `!` In y versust'ahead of means to the left of' while in `y` VERSUS `x` 'ahead of means to the right of' if the wave travels in positive `x-`direction and VICE versa.