91Ó°ÊÓ

Diffraction is a phenomena in which the interference or the bending of waves occurs around the corners of the opening or obstacle through or on which it strikes.

The diffraction formula is following,

$$\begin{gathered} \mathrm{²Ôλ}=2\mathrm{»å²õ¾\pm ²Ôθ} \\ \mathrm{λ}=\text{wavelength} \\ \mathrm{d}=\text{spacing} \\ \mathrm{θ}=\text{bragg angle} \\ \mathrm{n}=\text{order of diffraction} \end{gathered}$$

The spacing between reflecting plans is, $d=\text{0.94} \text{nm}$.

The bragg angle is, $\mathrm{θ}=2.00°$.

As the graph is running from 0 degree to 2 degrees the shortest wavelength wave is present at around the 0.75 degrees.

So putting all the values we will get shortest wavelength

${\mathrm{λ}}_1=2d\sin {\mathrm{θ}}_1$

Substitute all the value in the above equation.

$$\begin{gathered} {\mathrm{λ}}_1=2\left(\text{0.94} \text{nm}\right)\sin 0.75° \\ {\mathrm{λ}}_1=0.025 \text{nm} \\ {\mathrm{λ}}_1=25 \text{pm} \end{gathered}$$

As the graph is running from 0 degree to 2 degrees the longest wavelength wave is present at around the 1.15 degrees.

So putting all the values we will get longest wavelength

${\mathrm{λ}}_2=2d\sin {\mathrm{θ}}_2$

Substitute all the value in the above equation.

$$\begin{gathered} {\mathrm{λ}}_2=2\left(\text{0.94} \text{nm}\right)\sin 1.15° \\ {\mathrm{λ}}_2=0.038 \text{nm} \\ {\mathrm{λ}}_2=38 \text{pm} \end{gathered}$$

Hence the longest wavelength is,$38 \text{pm}$ .