Explanation

(c) Crystal structure is explored through the diffraction of waves having a wavelength comparable with the interatomatic spacing ($10^{- 10}$m) in crystals. Radiation of larger wavelength cannot resolve the details of structure, while radiation of much shorter wavelength is diffracted through inconveniently small angles. Usually diffraction of X-rays is employed in the study of crystal structure as X-rays have wavelength comparable to interatomic spacing.