question_answer

A progressive wave travelling along the positive x-direction is represented by \[y\left( x,\text{ }t \right)=A\sin \]\[(kx-\omega t+\phi )\]. Its snapshot at \[t=0\]is given in the figure: For this wave, the phase \[\phi \]is :                                         [JEE Main Held on 12-4-2019 Morning]

A) \[0\]     

B)               \[-\frac{\pi }{2}\]

C) \[\pi \]  

D) \[\frac{\pi }{2}\]

Correct Answer: C

Solution :

\[y=A\sin (kx-wt+\phi )\]at \[x=0,t=0,y=0\] and slope is negative \[\Rightarrow \phi =\pi \]