Q18 / 90 · KVPY 2011 (SB/SX) · Chemistry

To obtain a diffraction peak, for a crystalline solid with interplane distance equal to the wavelength of incident $X$-ray radiation, the angle of incidence should be

  • A
    $90^{\circ}$
  • B
    $0^{\circ}$
  • Correct answer
    C
    $30^{\circ}$
  • D
    $60^{\circ}$

Solution

From Bragg's equation $\begin{array}{l} \mathrm{n} \lambda=2 \mathrm{~d} \sin \theta \\ \mathrm{d}=\lambda, \mathrm{n}=1 \\ 1 \times \lambda=2 \times \lambda \sin \theta \\ \sin \theta=\frac{1}{-} \\ \theta=30^{\circ} \end{array}$

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

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