As is known, the air around us is a combination of several gases, so is a good insulator.In particular, because in many cases it is possible to avoid the need for additional layers of insulating material around a conductor.Today we talk about what is the dielectric constant of air.But first, perhaps, start with a definition of what is meant by the term "dielectric".
All substances, depending on the ability to conduct an electric current conventionally divided into three large groups: conductors, semiconductors and dielectrics.The first has a minimal restrictive direction of passage of charged particles thereon.The biggest group of them - are metals (aluminum, copper, iron).The second conductive under certain conditions (silicon germanium).But the third electric resistance is so large that the current does not pass thereon.A striking example - the air.
What happens when matter falls into the range of the electric field?For conductors answer is obvious - an electric current (of course, if there is a closed circuit, which provides the "way" for the particles).This happens due to the fact that changes the way of interaction between charges.Completely different processes occur under the influence of the field on the dielectric material.When studying the interaction of particles with an electric charge, it has been observed that the strength of the interaction is dependent not only on the numerical values of the charge, but also from the environment, separating them.This important feature is called "dielectric constant of the material."In fact, it is a correction factor, since it has no dimension.It is defined as the ratio of the strength of interaction in vacuo to a value in any environment.The physical meaning of the term "dielectric constant" is the following: This value shows the degree of weakening of the electric field of the dielectric material in comparison with the vacuum.The reason for this phenomenon is that the molecules of the material requires an energy field in the conductivity of the particles, and polarization.
known that the dielectric constant of air is unity.A lot or a little?Let's face it.Now there is no need to rely on their own numerical value constant for the most common substances as these data are given in the respective tables.Incidentally, this table is taken from the value of air, equal to one.The dielectric constant of air is almost 8 times lower than, for example, Micarta.Knowing this number, as well as the value of the charges and the distance between them, it is possible to calculate the effect of their interaction provided an air separation medium or plate Micarta.
formula for the following power:
F = (Q1 * Q2) / (4 * 3.1416 * E0 * Es * (r * r)),
where Q1 and Q2 - the value of the charges;E0 - permittivity in vacuum (a constant equal to 8.86 degrees 12);Es - dielectric constant of air ("1" or the value of any other material, the Table);r - the distance between the charges.All dimensions are taken in accordance with the SI system.
Do not confuse two different concepts - "air permeability" and the permittivity.Magnetic is another characteristic of any substance, also represents a factor, but its meaning is different - the relationship of the field strength and the values of the magnetic induction in a particular matter.The formulas used benchmark - the permeability for vacuum cleaner.Both the first and second terms are used to perform calculations of various electrical devices.
