Answer to Question #148161 in Mechanics | Relativity for Alfraid

Question

What is bragg equation.

Answer 1

Bragg's law provides the condition for a plane wave to be diffracted by a family of lattice planes: 2dsinθ=nλ. where d is the lattice spacing, θ the angle between the wavevector of the incident plane wave, k_o, and the lattice planes, λ its wave length and n is an integer, the order of the reflection.

Let's use explaining by the questions.

How is Bragg's Law calculated?

n * λ = 2 * d * sin(θ) ,

1. n is the positive integer, the order,
2. λ [m] is the wavelength of the X-ray,
3. d [m] is the interplanar distance, the distance between consecutive layers of atoms,
4. θ [rad] is the angle of the incident X-ray.

how can we imagine on the grapgh?

nλ = 2 d sin θ

 where λ is the wavelength of the electrons, d is the spacing of the crystal planes and n is an integer.

A simple way to derive the Bragg equation is as follows. The path difference between electrons scattered from adjacent crystal planes is 2d sin θ. For constructive interference between the two scattered beams the difference must be an integer multiple of electron wavelengths, nλ which gives the Bragg equation.

What is the value of n in Bragg's law?

The condition for reflection – the Bragg's law. Equation [39] is the Bragg's equation. 'Reflected' waves that do not obey this rule will interfere destructively. In eqn [39], the value n gives the 'order' of the diffraction.