Question

Calculate the angle at which first order reflection will occurs in an X-ray spectrometer when x ~ rays of wavelength \[\ce{1.54 \overset{\circ}{A}}\] are diffracted by the atoms of a crystal given that inter planer distance is \[\ce{0.04 \overset{\circ}{A}}\]

Options

• 13°

• 11°

• 9°

• 7°

Answer 1

11°

Explanation:

According to Bragg equation: `nlambda` = 2d sin qθ

For First order reflection n = 1; λ = \[\ce{1.54 \overset{\circ}{A}}\]; d =  \[\ce{4.04 \overset{\circ}{A}}\]

sin θ = `(nlambda)/(2d) = (1 xx (1.54A^circ))/(2 xx (1.54 A^circ)) = (1 xx (1.54 A^circ))/((0.08)(A))`

sin θ^–1 (0.191) = 11°