If I establish a permanent electric charge on some volume of material (as in an electret) and then move that material through space — is that motion equivalent to a current in a wire?
Also, since a current through a loop of wire generates a magnetic field, would spinning an electret generate a magnetic field as well? [Update: to be clear I mean a symmetrical spinning, i.e. either a monopolar electret or rotating a dipole charge along its own axis without flipping the field polarity.]
Moving an electret is not equivalent to current in a wire, as you say. However, it is current. The positive and negative poles of the electret are physically separated, so a moving electret corresponds to physically separated currents in opposite directions. That makes a magnetic field.
Furthermore, the electret is surrounded by an electric field. If you move the electret, that field changes, and you get a displacement current. That induces a magnetic field.
It's analogous to a magnet. A moving magnet makes an electric field. A moving electret makes a magnetic field.
Any motion of electric charges is an electric current. That's the very definition of an electric current.
Any electric current generates a magnetic field (see Biot and Savard law, or Maxwell-Ampère equation). If this current isn't constant in time, you might generate an electric field at the same time, since both fields are interdependent outside of the static case.
