The Electrical Conductivity (Time-Harmonic) subnode is available from the context menu (right-click the Electrical Material Model parent node) or from the Physics toolbar, Attributes menu. This adds ohmic conductivity to the material. Because the physics interface solves for the charge balance equation (that is, electrostatics or quasi-statics) this conductivity would lead to a time integral of the ohmic current in the equation. This feature can therefore only operate in a time-harmonic study.