BRAGG'S EQUATION -- BRAGG'S LAW
X-rays are electromagnetic radiations with high energies and wavelengths of the order 〖10〗^(-10) meter. These rays can be diffracted whenever they meet barrier with one or more openings that is about the same size as the wavelength. The layers of atoms or ions in crystals are separated by a distance of around 100 or 200 pm, which is the right range to cause X-rays to be diffracted. Thus layers of atoms in a crystal act as a diffracting for X-rays.