| Electric Point Source (Monopole): An monopole source of electric fields. Place between one and ten (five in Dipole Playground) point sources anywhere in the simulation window. With Select depressed, you can move the point source. In the point source's Properties Box, you can change the point source's strength (that is, its charge) and set the sign of the charge. If, under sign, you choose neutral, the charge on the electric point source is zero, regardless of what the strength field reads. You can also choose whether or not to show the monopole strength or the sign of the charge.