Electromagnetic waves can be polarized, reflected, refracted, diffracted or interfere with each other. The refracted beam of coloured light symbolises unity diffracted, leaving an absence of unity. Diffraction is less than at lower frequencies, although they can be diffracted by building edges. The finer the grating spacing, the greater the angular separation of the diffracted beams. When this beam illuminates the hologram, it is diffracted by the hologram's surface pattern. Each is further diffracted by the third grating. These are further diffracted by a second grating of period P into four beams. Single spots appear only when the beam is diffracted by a single crystal. The incident light is diffracted by the slits into uniform spherical waves. This condition allows a single incident beam to be diffracted in infinitely many directions. If the slit width is small, light passing the slits is diffracted heavily causing crosstalk. X-rays are usually not diffracted from atomic nuclei, but only from the electrons surrounding them. Users extract non-qualitative data from the kinematically diffracted electrons. Most of the diffracted light falls between the first minima. The diffracted plane wave has a wave vector formula 4.