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X-ray diffraction
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Bragg's law reveals crystal structure.
2d sinθ = nλX-rays reflect from crystal planes and interfere constructively when 2d sinθ = nλ (Bragg's law). Used to find crystal and biological structures like DNA.
d = 0.2 nm, λ = 0.154 nm: first order at 22.6°.
θ is measured from the plane.
In more detail
X-ray diffraction uses the regular spacing of atoms in crystals to scatter X-rays, forming patterns that reveal crystal structure. Bragg's law nλ = 2d sin θ describes the condition for reflection.
Real-world uses
- X-ray crystallography determined the structure of DNA.
- Materials scientists use diffraction to identify crystal phases.
- Crystallographers use X-ray diffraction to determine the structure of DNA, proteins and metals.
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Frequently asked questions
What is Bragg's law?
nλ = 2d sin θ, giving the angles where scattered waves reinforce.
Why does it need crystals?
Because crystals have regular atomic planes that scatter X-rays coherently.
What does the Bragg law tell me?
It gives the angle at which X-rays reflect strongly from a set of planes spaced by d in a crystal.
Related topics in Atomic & Nuclear Physics
Characteristic X-rays · Continuous X-ray spectrum · Moseley's law · Electron configuration · Atomic mass unit · Nucleus composition