| Electric Dipole Object (non-source): Place an electric dipole on a Rod by clicking in the vicinity of, but not on, the target rod. You may place up to four electric dipoles. Although you can place multiple dipoles (electric and magnetic) on one rod, there are few reasons to do so. In the dipole's Properties Box, you can make it a temporary dipole (conductor or insulator [default]) or a permanent dipole (always an insulator). The representation of the dipole depends on this choice (see pictures below). You can also show (default) or not show the Model View and the Microscopic View of the dipole.
Temporary (Insulator) | Temporary (Conductor) | Permanent (Insulator)
The purpose of the dot at one end of the dipole is simply to distinguish it from the other end. On permanent dipoles, the dipole end with the dot is always the negative end. The dot in the middle is simply the rod to which the dipole is attached. The dipole rotates freely on the rod. It responds to electric sources (the dipole source and the monopole [point source]) when they are present, and rotates randomly when no sources are present. The electric and magnetic dipole objects are sometimes called victims. This term illustrates the distinction between these dipoles and the dipole and monopole sources. The fields generated by the dipoles modeled by the victim elements are much weaker than the fields generated by the source elements. In fact, in the simulator, the victim elements don't generate fields at all. Thus, the victims are effectively "at the mercy" of the stronger sources.