The spacing between atoms in KCl crystal is 3.1 × 10−¹⁰ m.At what angle from the surface will a beam of 2.23 × 10−¹¹-m x-rays be constructively scattered? A)30° B)2.1° C)0.11° D)20° E)64°

Question

Quizplus · Accepted Answer

The Bragg's law states that constructive interference occurs when 2d sin θ = nλ, where d is the spacing between the planes of the crystal, θ is the angle of incidence, λ is the wavelength of the X-ray, and n is an integer (1, 2, 3...).

Rearranging the equation gives θ = sin^-1(nλ/2d). Substituting the given values gives θ = sin^-1((1)(2.23 × 10^-11 m)/(2)(3.1 × 10^-10 m)) = 2.1°. Therefore, the answer is B.

The Spacing Between Atoms in KCl Crystal Is 3