How does Davisson and Germer experiment indicate the wave nature of electrons? I know how the experiment is done but I cannot understand the relation between this experiment and the wave nature of electron.
The Davisson and Germer experiment used a crystal to scatter electrons. A crystal, as used in this case, is a solid with a periodic structure. So, when the electrons impinge on the crystal and you observe the result, what you see is a pattern (diffraction) that can only be understand as a wave phenomena.
For a fixed periodicity of the crystal, the scattering of waves will result in peaks at set angles that is determined by this period, and the wavelength of the wave (in this case electrons). So, by causing electrons to impinge on the crystal and then moving a detector, that measures electrons, one finds that at certain angles there is a lot of electrons, and at other angles there is a null of electrons. This is what the data shows. If the electrons weren't acting as a wave then you would have a much different result that you can think of as just baseballs scattering.