Q98 / 110 · VITEEE 2022 · Physics
The glancing angle in a X-rays diffraction experiment is \(30^{\circ}\) and the wavelength of the \(\mathrm{X}\) rays used is \(20 \mathrm{~mm}\). The interplanar spacing of the crystal diffracting these X-rays will be
- A\(40 \mathrm{~nm}\)
- Correct answerB\(20 \mathrm{~nm}\)
- C\(15 \mathrm{~nm}\)
- D\(10 \mathrm{~nm}\)
Solution
Using formula
\(\begin{aligned}
& 2 \mathrm{~d} \sin \theta=\mathrm{n} \lambda \\
& \mathrm{d}=\frac{\mathrm{n} \lambda}{2 \sin \theta}=\frac{1 \times 20 \times 10^{-3}}{2 \sin 30^{\circ}}
\end{aligned}\)
\(\mathrm{d}=\frac{20 \times 10^{-3}}{2 \times \frac{1}{2}}=20 \mathrm{~nm}\)
Hence, the correct answer is option: 'B'.