Volume conductor
= Volume conductor
A <volume conductor> is a conducting three-dimensional medium through which <electric currents> flow. In the quasistatic bioelectric model, the total <current density> is $\mathbf J=\mathbf J^p-\sigma\nabla u$, comprising an impressed source current and its Ohmic return current. <Electric charge conservation> gives $\nabla\cdot(\sigma\nabla u)=\nabla\cdot\mathbf J^p$. An insulating boundary has zero normal total current.