Crystal structures are studied by x-ray diffraction method.
It is due to the interatomic differences and interplanar distances in a crystal are in the range of wavelength of x-rays.
Only in the case of x-rays diffraction is possible.
Path difference = BC + CD
= AC sinθ + AC sinθ
= d sinθ + d sinθ
= 2d sinθ
According to the Bragg’s
Path Difference α λ
2d sinθ α λ
2d sinθ = nλ
d = distance between atomic layers