There is a stereotype in society according to which matter can be considered only that which not only really exists, but also is visible. This belief is only partially true. One of the clearest examples of invisible matter is the electrostatic field. Magnetic and electric fields are a special kind of it. This is quite simple to verify if we consider the electrostatic field and its characteristics.
As early as 1785, Sh. Coulomb discovered and justified the law on the force of interaction of two point bodies with electric charges. However, it remained unclear exactly how the exposure was transmitted. A number of experiments were carried out, in particular, when the charges were located in a vacuum. The law was respected. This suggests that the usual intermediate medium is not needed to transfer power. Subsequently, J. Maxwell (based on the work of Faraday) discovered an electrostatic field in a vacuum. It turned out that the field always exists around the charges, regardless of the type of environment, and ensures their interaction.
Since the field is material, it “obeys” Einstein’s formulas and propagates at the speed of light. The electrostatic field got its name due to the fact that it is characteristic of motionless charges ("static" - rest, equilibrium). The force discovered by Coulomb is called electric. It describes the intensity with which the field acts on the charge introduced into it.
One of the characteristics that an electrostatic field has is its intensity. Indicates the degree of interaction of point charges. For the study using the so-called test charge, the introduction of which in the field does not distort the latter. Usually it is taken equal to 1.6 * 10 in the degree of -19 pendant. If the tension is denoted by the letter "E", then we get:
E = F / Q,
where F is the force affecting the unit charge Q (for example, test). The use of the Coulomb law for calculations requires taking into account the dielectric constant of the medium.
An electrostatic field acts on any number of charges, and a complex system of interactions arises. The strength of the system can be considered from the point of view of superposition, therefore, the total effect of the N-number of charges is the vector sum of all field strengths. By the way, the concept of “tension line” (a term known from the school physics course) arose thanks to Faraday, who schematically depicted the field with lines at each arbitrary point coinciding with the electrostatic field intensity vectors. Accordingly, the more such lines, the more intense the force. Unlike electromagnetic fields, in electrostatics, tension lines are not closed. It is also worth noting that in metals (and other conducting materials) there is no field strength due to the counter-directed action of the field of free charge carriers located in the structure of the crystal lattice. In fact, the forces quickly equalize, there is no current, and tension lines cannot penetrate into such a conductor.
In addition to vector quantities, the field can be described by scalar values taken at each (ideal case) point. In electrostatics, these values characterize the field potential. We can say that it corresponds to the value of potential energy for a unit positive charge at any given point in the field. Accordingly, the unit of measurement is Volt. It is determined by the ratio of the potential energy of the charge Q-probe to its value, that is, W / Q-probe.
The potential itself is equal to the work done by the forces of the electrostatic field, moving the charge from one point to another, infinitely distant.