Length of a string tied to two rigid supports is $40 \ cm$. The maximum wavelength (in $cm$) of a stationary wave produced on it is ... $cm$.

The figure shows an incident pulse $P$ reflected from a rigid support. Which one of $A, B, C, D$ represents the reflected pulse correctly?

In a standing wave on a string rigidly fixed at both ends:

$A$ string vibrates according to the equation $y = 5 \sin \left( \frac{2\pi x}{3} \right) \cos (20\pi t)$,where $x$ and $y$ are in $cm$ and $t$ is in $sec$. The distance between two adjacent nodes is .... $cm$.

$A$ standing wave having $3$ nodes and $2$ antinodes is formed between two atoms having a distance of $1.21 \; \mathring{A}$ between them. The wavelength of the standing wave is .... $\mathring{A}$

The velocity of waves in a string fixed at both ends is $2 \ m/s$. The string forms standing waves with nodes $5.0 \ cm$ apart. The frequency of vibration of the string in $Hz$ is