David wrote:
Displacement current is usually introduced as the virtual current that flows
through the dielectric of a capacitor. Does such a current really exist?

When one discharges a charged capacitor through a resistor,
the excess charge from one plate of the capacitor flows
through the resistor to the other plate of the capacitor
in order to equalize the charge on both plates. Since the
current is supposed to be the same all around a single
series circuit, it is *as if* current is flowing through
the capacitor's dielectric somewhat like current flows
through acid inside a car battery. Since actual current
flowing through the insulating dielectric would destroy
it, of course that current is only virtual and is called
displacement current. It can usually be treated *as if*
it were real.
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73, Cecil http://www.w5dxp.com