Question

If two waves of same frequency and amplitude superpose to produce resultant of the amplitude of either wave, then their phase difference is-

• A. $\pi$
• B. $2\pi /3$
• C. $\pi /3$
• D. $Zero$

Answer 1

The correct option is B $2\pi /3$

Let,

$\begin{array}{c}{x}_1=A\sin wt\\ x_2=A\sin \left(wt+\varphi \right)\\ x=x_1+x_2\end{array}$

$\therefore$ For resultant amplitude to be equal to

A $\varphi$ must be $\frac{2\pi }{3}$.

$\therefore$ phase difference is $\frac{2\pi }{3}$

$\therefore$ Option $B$ is correct answer.