Question

In the adjoining figure A, B, and C represents three progressive waves. Which of the following statement about the waves is correct?

• A. Wave C lags behind in phase by $\frac{\pi }{2}$ from A and B leads by $\frac{\pi }{2}$
• B. Wave C leads in phase by $\pi$ from A and B lags behind by $\pi$
• C. Wave C leads in phase by $\frac{\pi }{2}$ from A and lags behind by $\frac{\pi }{2}$
• D. Wave C lags behind in phase by $\pi$ from A and B leads by $\pi$

Answer 1

The correct option is A Wave C lags behind in phase by $\frac{\pi }{2}$ from A and B leads by $\frac{\pi }{2}$

According to the given figure, A attains mean position $T/4$ time earlier than C. So, C lags behind A by $\frac{\pi }{2}$, Also B attains the mean position $\frac{T}{2}$ time earlier.
Hence, B leads A by $\frac{\pi }{2}$.