The behavior of Capacitance Explained
A review in terminology using an example.
The most rudimentary capacitor is the parallel plate capacitor. It consists of a set of parallel plate separated by a slight distance. When a charge is applied to one of the two plates, the equivalent opposite charge occupies the other plate. Like charges repel, and opposites attract. The closer the two plates are together, the more they are attracted, the more charge density is drawn to the other side.A Parallel-plate capacitor has an Area a and plate separation D is defined with equation:
, where 
and C is the capacitance of the capacitor as measured in farads.
Capacitance in general is defined as:
, where Q is the charge in coulombs
and V is the differential voltage (high point - low point).
If one were to combine two equations together. One finds that:
In general, once a commercial capacitor is fabricated, the area and
distance of separation are unchangeable. So the only method of
increasing the the charge (Q) on the capacitor is to increase the
voltage applied. And even so, most commercial capacitors have
limitations in their designs which prevent high voltages. One major
limitation is that as voltage increases, the voltage will start to leak
to the other side. Another limitation is that if voltage is increased,
the repulsion force becomes great and results in heat and expansion of
materials inside the capacitor.
Sounds confusing? I confuse myself too... I'll attempt again, explaining from another
aspect.
Suppose you have a battery and charge the capacitor until its fully
charged. Now you disconnect all circuits from the capacitor. By
disconnecting the wires you ensure that the charge (in coulombs
or billions of individually charged electrons) are trapped inside the
capacitor on one plate, and a slew of positive charges on the opposite
plate. What happens (in parallel plate capacitor) if you double
the distance between the two plates... There are only 3 possibilities.
 Area can double |
 Charge can half |
 Voltage can double |
Of the 3 above possibilities only one is possible.
Area can't double since it is a physical limitation of the capacitor, and mass just can't grow.
Charge can't half, since electrons are suck inside the capacitor, not
free to leave.
Therefore, It must be that voltage doubles.
One can imagine some sort of physical device that applies tons of low
voltage in direct current to charge a capacitor. Which then, the
machine physically extends the separation of the two plate to induce a
large voltage. AND ZAP and lightening generator....