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

• Correct answer
  A

  $1.21 \stackrel{\circ }{\mathrm{A}}$

   
• B

  $1.42 \stackrel{\circ }{\mathrm{A}}$
• C

  $6.05 \stackrel{\circ }{\mathrm{A}}$

   
• D

  $3.63 \stackrel{\circ }{\mathrm{A}}$

Solution

The given standing wave is shown in the figure




As the length of loop or segment is $\frac{\lambda }{2}$

So the length of 2 segments is $2\left(\frac{\lambda }{2}\right)$

$\therefore 2\frac{\lambda }{2}=1.21 \stackrel{\circ }{\mathrm{A}}$

$⟹\lambda =1.21 \stackrel{\circ }{\mathrm{A}}$

Hence, the correct answer is option: 'A'.