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 answer
    B
    \(20 \mathrm{~nm}\)
  • 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'.

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