Imagine one plate of a capacitor connected to a terminal of a electric AC source. Imagine the other plate of the capacitor to the right is connected to the other terminal of the source. From the point of view of classic electronics, a capacitor with such AC signal behaves just like a wire, the signal pass without problems. But now imagine there is another plate to the left of the first plate of the capacitor, connected to any other point, but not to the source. (so finally, three plates, two makes a capacitor on a closed path over a source, and the other plate and one of the plates of the capacitor makes an "open path"). I think this plate will fell also the changes on the signal and there will be charge variations on that part of the "open path".(although the plate is not connected to the source, somehow, it is coupled to the capacitor), Will the disconected plate follow the charge changes on the capacitor? Will this charge changes (if exist) do work on a load on the "open path"? Will the AC source have to do more work with this kind of performance?