Calculate the angle at which second order reflection will occur in an X- ray spectrometer. When X – ray of wavelength 1.54 A$^{\large\circ}$ are diffracted by atoms of a crystal. The interplanar distance is 4.04$A^{\large\circ}$.

Answer 1

According to Bragg’s equation

$n\lambda = 2 d \sin \theta$

n = 2

$\lambda = 1.54A^{\large\circ}; d = 4.04 A^{\large\circ}$

$\theta=\sin^{-1}(\large\frac{2\times 1.54}{2\times 4.04})$

$\Rightarrow \sin^{-1}(\large\frac{1.54}{4.04})$$=\sin^{-1}(0.381)=22^{\large\circ}24'$

Hence (C) is the correct answer.