Working Principle of Capacitors

Imagine in front of you there are two iron plates, two long cables, and a 12-volt car battery that reads Yuasa that has just been charged. 

Then you arrange the two iron plates to be facing each other and parallel to a distance of only 1 cm. Using the two available wires you connect one iron with the positive pole of the battery, while the other iron you connect with the negative pole.

Then while wearing an Ant Man costume, you press the button on the base of your right index finger until you shrink, continue to shrink, while feeling a little nausea in the stomach, until finally reaching subatomic size.

And how surprised you are when you can see various miracles that exist in these other realms.

As you approach the iron plate atoms, your eyes widen at the sight of the positive iron plate atoms being left by the electrons.

With curiosity, you approach the atoms on the iron plate next to it that are connected to the battery’s negative pole. And you are even more curious, because seeing the iron atoms are actually approached by electrons, more and more, and increasingly accumulate.

A few moments later you are surprised. You see a change in phenomenon. 

The flow of electrons stops completely. But you feel the power of new energy stored in the atoms of two parallel steel plates. Sort of, a new battery.

Thus at a glance what is a capacitor when viewed from the perspective of Ant Man. And of course I was only joking about the existence of one of the Marvel superheroes. But for the illustration of the electricity phenomenon above, I am not kidding, that is exactly what happens to capacitors.

In fact, a capacitor is only an electrical component consisting of two electrical conductors flanking an insulator. Thus the symbol of the capacitor is shaped like that, which is like two parallel wires giving distance to each other. Empty between the two.

When the capacitor is connected to a DC voltage source, the electric current flowing from the battery will make the capacitor store more charge. At a certain point in time, the capacitor will reach its maximum capacity whose value is equivalent to the battery voltage.

If Q is the charge of the capacitor, and V is the electric voltage, then the relationship between the two – which is fine – can be said to be comparable as the equation below:

Q \approx V

Then if we enter a standard constant called capacitance (C), the above equation becomes:

Q = CV

If explored deeper, the capacitance value of a capacitor depends on 3 things: the permissivity value of the dielectric medium used, the surface area of ​​the metal plate area, and the distance between the two. 

The following are the three factors’ relationship with the capacitance value:

C = \ dfrac {\ varepsilon A} {d}

Then, is it true that the story above says that the capacitor after connecting with the battery will become a new battery?

Of course not.

There are some basic differences between batteries / capacitors and batteries. The following are:

Saving electrical energy in the form of chemical energySaving electrical energy in the form of electric charge
Having a constant voltage valueThe voltage value is not constant, depending on the value of the voltage source connected to the capacitor.
Electrical energy that comes out of the battery lasts for a long time.Electrical energy coming out of the capacitor if after being charged it is connected to a load (resistor), only for a moment is of great value and is immediately lost.