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From: Alan G3NOQ
Date: 22 Nov 2002
Time: 06:18:19
Remote Name: 20.138.254.2
Fathi - I think there is just a language confusion here. You can charge a capacitor from a battery but normally that does not mean it is dc, because it is only dc when the current and voltage are unchanging with time. In the language of differential equations, a dc circuit is a steady-state condition, after the initial transient has died away. . . . . While the capacitor is charging there is a displacement current, and another way of looking at it is the charge spreading out over the plates, but this is not yet dc. When the capacitor is fully charged to the supply voltage, that is dc and then there is no current and no displacement current. . . . In Maxwell's equations the displacment current density is dD/dt, or at a single frequency it is jwD. That is the definition as I understand it, and under that definition there is no displacement current in a dc circuit. . . . Best regards, Alan