Suppose you have a parallel plate capacitor that is disconnected from any power source and is discharged. At time $t=0$, the capacitor is connected to a battery. Make qualitative graphs of current ($I$) in the wire, charge ($Q$) on the positive plate, and voltage ($\Delta V$) across the capacitor over time.

• The capacitor is discharged.
• The capacitor is made up of parallel plates.
• The capacitor is connected to a power source at $t=0$.

• Graphs of $I$, $Q$, $\Delta V$$.

• The power source is connected correctly with respect to the capacitor and there are no other circuit elements (except for the wire).
• The wire itself has a small resistance, just so we do not have infinite current at $t=0$.
• Practically speaking, the capacitor becomes “fully charged” (with respect to the potential of the battery) at some finite time.

• We represent the setup below. The capacitor is pictured both disconnected and hooked up to the power source.

Before the capacitor is connected, we know that it is discharged, so there is a net neutral charge both on the wire and on the parallel plates. At time $t=0$, when the power source is connected, it brings with it an electric field, which the charges on the wire and capacitor do not immediately oppose. At time $t=0$ (or maybe slightly after 0, once the electric field has propagated at the speed of light), the electric field in the wire may look like this: