Quasistationary current contributions in electronic devices

In an electronic device, the current supplied to the electiodes is related to different types of processes inside the device: current density, change in spontaneous Polarization, and change in dielectfic properties. Two expressions for the electrode cull rent are derived: one is based on the time derivative of the Shockley-Ramo theorem, the other on the time derivative of the dielectfic tensor This result is illustrated for a switching liquid crystal device and a two-dimensional flux tube.