Bragg's Law
Condition for constructive interference in X-ray diffraction from crystal planes. Used to determine crystal structures and to create X-ray spectrometers.
Variables
Derivation
Path difference between rays reflecting from adjacent planes must equal whole wavelengths.
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- d = 2 m (Lattice spacing)
- θ = 3 ° (Angle of incidence/reflection)
- n = 4 (Order of diffraction (1, 2, 3...))
Result: λ = 0.05233596 m
Other modern physics formulas with the same quantities
- Photon Energy (Planck) (Quantum Mechanics) shares Wavelength
- Photon Momentum (Quantum Mechanics) shares Wavelength
Where this formula is listed
- Modern Physics formulas, under Quantum Mechanics, alongside Photoelectric Effect, Stopping Potential, Heisenberg Uncertainty Principle, Energy-Time Uncertainty and Time-Dependent Schrödinger Equation.
- In the modern physics list it comes after Photoelectric Threshold Frequency and before Electron Wavelength (Accelerated).
- Modern Physics formula sheet, one of 41 formulas printed with symbol keys and SI units.
- The full formula index, grouped by category and topic.
Common questions
What is the Bragg's Law formula?
Bragg's Law is written 2d sin θ = nλ. Condition for constructive interference in X-ray diffraction from crystal planes. Used to determine crystal structures and to create X-ray spectrometers. It belongs to Modern Physics, under Quantum Mechanics.
What are the units in 2d sin θ = nλ?
In SI units, d is lattice spacing, measured in m; θ is angle of incidence/reflection, measured in °; n is order of diffraction (1, 2, 3...) (dimensionless); λ is wavelength, measured in m.
How is the Bragg's Law formula derived?
Path difference between rays reflecting from adjacent planes must equal whole wavelengths. The result is 2d sin θ = nλ.