What is the electrical capacitance?

Often in school physics lessons, the teacher, explaining the topic of electricity, resorts to comparing the electric current with the flow of water. In many cases, although not always, to make it easier to understand the processes that occur, such a comparison is entirely acceptable. Actually, even the very word "current" is used specifically for liquids. And what is the capacity? This is one of the characteristics of the object, its ability to contain anything. For example, everyone knows that the capacity of the can is 3 liters. Obviously, the amount of accumulated water directly depends on the capacity of the vessel. So, if you take two buckets, for example, 8 and 12 liters, then they are equal in height, but only in diameter. The concept of "electric capacity" in this regard is very similar. For example, one of the parameters affecting the capacity is the dimensions. Electric capacity (EE) is the ability to accumulate and retain a certain amount of electricity. Any conductive material possesses a certain EE, depending on a number of parameters. The process of accumulation of charge is possible in the event that there is no possibility of its flowing over to another object possessing a larger capacity.

The electrical capacitance can be expressed through a formula that takes into account the ability to accumulate a charge (potential - v) and the value of the charge itself (q). Denoted by the letter "c":

C = q / v

The electric capacity is measured in farads. However, since this value is quite large, micro- and picofarads are more often used in modern electronic circuits. Large capacities are used only in specific devices and calculations. Accordingly, the prefixes "micro and pico" are 1 * 10 at -6 and -12 degrees. The processes that occur can be easily described through the electrical capacity of a solitary conductor.

Let us imagine a conductor in a nonconducting current medium in which there are no external fields. Connect it to the power source. Some electrons enter the material structure, creating an excess potential, that is, these charges can perform work under certain conditions (create a circuit). They are distributed over the surface with a certain density, which depends on the spatial configuration of the conductor and its dimensions. Around each point charge there is an electric field that affects all other sections of the conductor. The potential of such a solitary conductor is in direct proportion to the charge. The ratio of the given charge (q) to the potential (Fi) for the conductor under consideration is invariant, since it depends only on the dimensions (size, shape) and the dielectric constant of the medium. In the example, it is not for nothing that a solitary conductor is indicated. If there are other bodies next to it, the electric field of single charges will induce in the surrounding bodies the potential of the opposite sign, which will affect the final value (it will be less).

The simplest element that uses properties to accumulate an electric current is a capacitor. It is two conductors separated by a dielectric material. Its peculiarity is that the generated electric field is "bound" between the plates (opposite sections of conductors) and practically does not affect the surrounding bodies, and therefore the potential for external work is not wasted.

You can increase the capacity in several ways:

• Reduce the gap between the plates. Infinite reduction is impossible, since a breakdown of a nonconducting medium can occur, which leads to a loss of charge;
• Pick non-conductive material with high resistance to breakdown;
• Increase the area of the plates. In order to maintain acceptable dimensions of the capacitor, the spatial arrangement of the plates often changes. For example, two conductors are twisted into rings separated by an insulator.