Capacitor plate current skin effect

Thread starter FusionJim
Start date Jan 26, 2025
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Capacitor Current Plate

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The discussion centers on the skin effect and surface charge depth in capacitors, particularly comparing DC and AC conditions. It is established that for a charged capacitor with a DC potential, the surface charge depth is indeed very shallow, typically only a few atomic layers. When connected to an AC source, the surface charge depth does not increase; rather, the displacement current flows across the surface without penetrating deeper into the conductor. Dynamic changes in capacitance, such as moving one plate relative to another, cause charge redistribution on the surface but do not affect the depth of the surface charge. Overall, the behavior of the electric field and charge displacement in capacitors differs fundamentally from that in regular conductors.

Jan 30, 2025

FusionJim

Baluncore said:

A small positive patch, close to a large negative plate, will draw electrons out of the large plate surface. Since C = Q / V, the charge drawn out will be Q = C⋅V ; That is, for a fixed voltage, charge is proportional to the capacitance.

If the positive patch is then moved around on the plate, the mound of electrons on the plate surface will be dragged about, following the moving patch. A momentary surface current of electrons will flow, where the edge of the small moving patch, covers or uncovers the larger plate.

Well , is the surface current that you talk about parallel to the plate surface or perpendicular? Because @Ivan Nikiforov claims and shows even with an animation that there is only perpendicular movement of electrons due to the change in plate location. You left out that distinction but that is an important one, which causes some misunderstanding to me.