Magnetic forces are generally quite manageable on the human scale. The positions and geometry of the magnets within the magnet arrays shown in Fig. (a), for example, are easily fixed within a 3D-printed plastic housing and readily allow classroom demonstration. In fact, the pair of arrays can be held one in each hand, and the increasing repulsive forces are felt as the arrays are pushed together… right up until they slam together as the potential barrier is overcome! In contrast, the analogous electrostatic array in Fig. , having the same centimeter scale and geometry as the magnetic "Coulomb" barrier arrays, would produce enormously strong forces…similar in magnitude to the gravitational attraction between Mount Fuji and planet Earth! A classroom demonstration of a potential barrier arising between the electrostatic arrays shown in 1(b) is, therefore, quite problematic. It is possible, however, to visualize the resulting barrier using "heat" map representations of the electrostatic fields.