Schematic view of an unipolar inductor. The unperturbed wind’s magnetic field B₀ and velocity v₀ are almost, but not exactly, perpendicular. The electric field E₀ created by the unipolar inductor is perpendicular to these two vectors; it induces an electric current (of density j) along the body. This current then goes into the interplanetary medium, forming two structures, each of them made of an outwards and an inwards flow. The current density j flowing along the planet is the cause of a j × B force density that is the topic of the present study.