batteriescapacitordischarge
So say you a typical setup like in this diagram.
How does current flow while the capacitors charge? To elaborate, what is the mechanic that makes capacitors mimic the functionality of a wire instead of acting like the gap in the wire that they are?
When the capacitor is fully charged, the left plate is positive and the right plate is negative right? So does that mean when you disconnect the battery the capacitor discharges in the opposite direction that the batteries current was in?
If it's fully charged there's no current. When not or partly charged there will be current if you apply a voltage to it. The current curve depends on how your voltage source is connected. If you supply a constant current the voltage will rise linearly, if you charge over a resistor it will rise exponentially. That's because the rising voltage will cause the voltage drop over the resistor to become smaller and smaller, and hence the current through it will also decrease. A lower current means that charging goes slower.
How fast the capacitor charges depends on both the resistor's and the capacitor's value. The larger the resistor the slower the capacitor charges, and it also charges slower if the capacitance is greater. The exponential curve is said to have a time constant \$RC\$. After about \$5 \times RC\$ the capacitor is charged to 99%.
9V. The capacitor's rating has nothing to do with it, that only determines how high a voltage you can apply. Just look at what voltage is available, and that's 9V. Just take care that the capacitor is fit for the supplied voltage. You can safely charge a 16V capacitor to 9V, but not to 25V.
Inductors store energy in the magnetic field generated when current passes through them. When the supply is removed, the collapsing magnetic field induces a current flow in the same direction that it was traveling when it generated the magnetic field in the first place. This is why it is used as one of the storage devices in switching power supplies; the capacitor maintains the same voltage, and the inductor maintains the same current.
simulate this circuit – Schematic created using CircuitLab
(But don't try to actually build this circuit.)
Best Answer
The mechanism is electrostatic repulsion -- the Coulomb force. The battery forces extra electrons onto the negative plate of the capacitor. The excess charge pushes an equal number of electrons off of the other plate and into the rest of the circuit. To the rest of the circuit, it looks like there's a current through the capacitor, since electrons go into one end and come out the other.
If you replace the battery with a short circuit, the capacitor will indeed produce a discharge current in the opposite direction of the charging current. (It's sort of like a spring.) If you replace the battery with an open circuit, no current flows and the capacitor remains charged.