In the Electron Diffraction simulation, a circle represents the front view of the glass globe of an electron diffraction tube. A 6.3 V source represents the source that feeds the tube filament that is heated and releases electrons through the thermionic effect, also called the Edson effect. A cursor represents the control of a high voltage source that accelerates electrons. Accelerated electrons impinge at high speeds on a polycrystalline graphite sample (not visible) that is placed inside the diffraction tube. Electrons are diffracted by the graphite structure and form constructive interference rings on the fluorescent surface of the glass globe. Interference rings show the wave behavior of electrons whose wavelength is a function of electron velocity. The radii of the observed circles are related to the wavelength of the electrons and to the distances between the planes of atoms in graphite crystals. A ruler allows the determination of the radii of the observed interference rings. The analysis of the values found for the radius of the circles observed as a function of the electron velocity and the dimensions of the glass globe allows the determination of the distance between the graphite atoms planes.