Capacitance and Electron Movement in the Dielectric

Capacitors store charge on parallel plates. The question I'd like to answer is how are the electrons moving in order to store the charge. Electrons flow into the negative plate of the capacitor during charging. An equal number of electrons flow out of the positive terminal during this charging process.

Electrons flow into and out of a capacitor. There are also reports that the dielectric region in the middle of the capacitor is polarized when charged. Dipole type molecules form dielectrics whose poles line up against the incident electric field. This description of capacitor action seems static and lifeless. Clearly there is a lot going on in a charging or charged capacitor.

The statistics of electron flow involve multiple interactions with a conducting lattice or a non-conducting dielectric. How fast electrons back-fill incident electrons must also be examined. If an electron travels into a dielectric material with a high amount of potential energy that electron will leave behind a hole. The hole draw an electron from the dielectric. This enables the polarizing electrical engineering profs talk about.

If millions of electrons are observed we begin to notice a pattern of behaviour during charging or in a charged capacitor. We observe electrons entering the dielectric with a Poisson type distribution. A certain number of electrons enter the dielectric and then are replaced with a less energetic electron. This continues until the energy in the electrons in the dielectric is equal to the charging voltage. Then the capacitor is said to be charged.

Electrons dive through the dielectric with relatively high kinetic energy. These particles bump back towards the negative plate. This action pushes electrons away at the positive plate. These electrons return toward the electromotive force where they are pumped with negative voltage towards the negative end of the capacitor or elsewhere in the circuit.