Question

At any instant a wave travelling along the string is shown in figure. Here, if point A is moving upward, the true statement is

• A. the wave is travelling to the right
• B. the displacement amplitude of wave is equal to displacement of B at this instant
• C. at this instant, C also directed upward
• D. 1 and 3

Answer 1

Answer: (B)

the displacement amplitude of wave is equal to displacement of B at this instant

The figure shows a sinusoidal wave which is given by:
$y=-A\cos \omega t$, where $A$ is the amplitude of the wave which will vary with time as a cos function. At some certain values of t it will reach the maximum $A$. Here in the figure, B is the maximum point of the wave i.e. the displacement amplitude of wave.