Bragg's law states that the difference in path length between
beams scattered of two adjacent lattice planes of a crystal has
to be a multiple of the wavelength, 
. Mathematically, this is written as:
= 2 d sin(
)
where n is an integer number, d is the
distance between two
crystal planes and 2
is the scattering angle, i.e. the angle between the incoming
and outgoing beams.
