Left to their own devices, two electric charges of the same name want nothing to do with each other. They fly as fast as they can. Thus, if the particles are forced to move towards each other (and this happens, for example, when accumulating a charge), they resist this in every possible way, and in order to increase the charge concentration density in the conductor, a certain energy must be expended.
In a static state, this energy is not used and is irretrievably lost. It is stored as an electric field - a kind of tension in the space between charged particles - until the concentration of charges decreases, and they regain the ability to move freely.
In this case, the charges use the accumulated energy of the electricfield to acquire acceleration on its way.
A capacitor is an electrical circuit component specifically designed to store an electric field.
The energy of the electric field of a capacitor is the basis of its use in numerous electrical and electronic devices.
Simple logic dictates that a capacitor charged to a voltage of V will require QV joules of energy to reach a new state, and this value is precisely the energy of the electric field of the capacitor, stored in it and ready for use.
Unfortunately, common sense fails here. Just because you feel good after drinking a beer, it does not mean that you will feel exactly twice as good after drinking the second one.
In fact, as the charges approach, they resist it more and more fiercely. Obviously, here we are dealing with a non-linear process.
Let's see how the energy of the electric field of a capacitor is determined based on a simple experiment.
It is known that the current is defined as the speed with which the charge moves. Therefore, if you connect the capacitor to a source of stabilized current, the charge Q will accumulate on the plates at a constant rate.
Suppose we take an uncharged capacitor and connect it to a power supply that provides constant charging current I.
Voltage on the capacitor starts from zero and increaseslinearly until the capacitor is fully charged. After that it stops. Let's call this value the maximum voltage V.
The average voltage across the capacitor during charging is (V/2), and the average power, respectively, is I(V/2). The capacitor was charged in time T seconds, so the energy of the electric field of the capacitor stored in the process of charging is TI (V/2).
W=1/2QV=1/2CV
Despite the existence of a huge number of sizes, the capacitor device is not very diverse.
Most of them consist of two parallel plates separated by a dielectric. Sometimes, to save space, this sandwich is rolled up like a roll. And in some cases they have several layers, connected in a certain way.
Calculating the capacitance of a capacitor consisting of two metal plates, with known physical dimensions, is usually not difficult, as well as calculating the resulting capacitance when capacitors are connected in series or in parallel.
