Bragg law was derived in 1913 by
English physicist
Sir W.H. Bragg, and his son
Sir W.L. Bragg. It was a result of their experiments to try to explain why the
cleavage faces of crystals appear to reflect
X-ray beams at certain angles of
incidence. The law states that:
nλ = 2d sin Θ
Where:
Θ is the angle of incidence
λ is the wavelength of the incident X-ray
d is the distance between atomic layers in a crystal
n is an integer which is dependant on the order of reflection
The equation itself is a simplification of work done by Max von Laue, a German physicist who discoved X-ray diffraction in 1912. Bragg law is primarily used to work out the atomic structure of crystals by calculating wavelength from diffraction angle data . The Braggs were awarded the Nobel Prize in physics in 1915 for their work.