Phenomena such as dielectricsusceptibility and dielectric constant, are found not only in physics, but also in ordinary life. In this regard, it is necessary to determine the values of these phenomena in science, their influence and use in everyday life.
Tension is a vector quantity inphysics, which is calculated from the force affecting the unit positive charge placed at the field point under study. After a dielectric is placed in an external electrostatic field, it acquires a dipole moment, in other words, it is polarized. In order to quantitatively describe polarization in a dielectric, polarization is used - a vector physical indicator, calculated as the dipole moment of the dielectric volume value.
Tension vector after crossing the facebetween two dielectrics undergoes spasmodic changes, causing this interference during the calculation of electrostatic fields. In connection with this, an additional characteristic is introduced - the electric displacement vector.
With the help of dielectric constant canfind out how many times a dielectric can weaken an external field. For the purpose of the most rational explanation of electrostatic fields in dielectrics, an electric displacement vector is used.
Absolute dielectric constant of mediumis a coefficient that is included in the mathematical notation of the Coulomb law and the equation of the relationship between the intensity of the electric field and electrical induction. The absolute dielectric constant can be represented as a product of the relative coefficient of the dielectric constant of the medium and constant electricity.
Dielectric susceptibility, calledthe polarizability of a substance is a physical quantity that can be polarized under the influence of an electric field. This is also the coefficient of linear coupling of the external electric field with the polarization of the dielectric in a low field. The dielectric susceptibility formula is written as: X = na.
In most cases, dielectrics have a positive dielectric susceptibility, and this value is dimensionless.
Ferroelectricity is physicala phenomenon present in certain crystals, called ferroelectrics, at certain temperature values. It consists in the appearance of spontaneous polarization in a crystal, even without an external electric field. The difference between ferroelectrics and pyroelectrics lies in the fact that in certain temperature ranges their crystalline modification changes, and the random polarization disappears.
Electricians in the field do not behave like conductors,however, they have common features. A dielectric differs from a conductor by the absence of free charged carriers. They are there, but in minimal quantities. In a conductor, an electron that moves freely in the metal crystal lattice becomes a similar charge carrier. However, electrons in a dielectric are bound to their own atoms and cannot move easily. After making dielectrics in a field with electricity, electrification appears in it, like a conductor. The difference from a dielectric is that electrons do not move freely throughout the volume, as it flows in a conductor. However, under the influence of an external electric field from the inside of a substance molecule, a slight displacement of charges occurs: the positive will be displaced in the direction of the field, and the negative - vice versa.
In this regard, the surface acquirescertain charge. The procedure for the occurrence of a charge on the surface of a substance under the influence of electric fields is called dielectric polarization. If in a uniform and non-polar dielectric with a certain concentration of molecules all particles are the same, then the polarization will also be the same. And in the case of the dielectric susceptibility of the dielectric, this value will be dimensionless.
Due to the polarization process in volumedielectric substances appear uncompensated charges, called polarization or related. The particles that have these charges are in the charges of the molecules and, under the influence of an external electric field, are displaced from the equilibrium position without leaving the molecule in which they are located.
Bound charges are characterized by superficialdensity. The dielectric susceptibility and permeability of the medium determines how many times the force of the coupling of two electric charges in space is less than the same indicator in a vacuum.
Relative air susceptibility andpermeability of most other gases in standard conditions is nearing unity (due to the small plane). The relative dielectric susceptibility and the dielectric constant in ferroelectrics is tens and hundreds of thousands on the surface of the separation of a pair of dielectrics with different indices of the absolute dielectric constant and susceptibility of the substance, as well as equal between the tangential components of intensity.
Among the many practical situations occurencounter with the transition of current from a metal body to the outside world, while the specific conductivity of the latter is several times less than the conductivity of a given body. Such situations can occur, for example, during the passage of a current through metal electrodes buried in the ground. Often use electrodes made of steel. If the task is to determine the dielectric susceptibility of glass, then the task will be somewhat complicated by the fact that this substance has the ion-relaxation property, due to which there is a slight delay.
At the boundary of a pair of dielectrics with differentin the presence of an external field, polarization charges appear with different indices and with different surface densities. This is how a new condition of refraction of the field line is obtained during the transition from a dielectric to another.
The law of refraction in the case of current lines can be considered in its form to be analogous to the law of refraction of displacement lines on the verge of two dielectrics in electrostatic fields.
Every body and substance of the world hascertain electrical properties. The reason for this lies in the molecular and atomic structure - the presence of charged particles that are in an interconnected or free state.
Если на вещество не влияет внешнее поле, то такие parts are arranged, balancing each other, in the total volume, without creating additional electric fields. If the application of electric energy happens outside, inside the existing molecules and atoms, a redistribution of charges will appear, which will lead to the appearance of its own internal field, which will be directed towards the external one.
When designating the applied external field as E0, and internal E ", then the entire field E will be the sum of these values.
All substances in electricity are divided into:
This classification has existed for a long time, but it is not entirely accurate, since science has long since discovered bodies with new or combined properties of a substance.
As conductive substances can actenvironments in which free charges are present. Often metals are considered as such matters, since their structure implies the constant presence of free electrons capable of moving within the entire cavity of a substance. The dielectric susceptibility of the medium allows to be a participant in the thermal process.
Если проводник находится в изоляции от влияния external electric field, then inside it appears a balance between positive and negative charges. This state disappears immediately when a conductor appears in an electric field, which with its energy redistributes charged particles and provokes the appearance of unbalanced charges with a positive and negative value on the outer surface.
This phenomenon is called electrostatic induction. Appeared under its action, the charges on the metal surface are called induction charges.
Induction charges arising in the conductorcreate their own field, compensating for the influence of the external field inside the conductor. In this regard, the indicator of the total total electrostatic field will be compensated and equal to 0. The potentials of each point inside and outside are equal.
This result indicates thatfrom inside the conductor (even with a connected external field) there is no difference in potentials and no electrostatic field. This fact is used in shielding due to the use of the method of electro-optical protection of a person and field-sensitive electrical equipment, especially high-precision measuring instruments and microprocessor technology.
Relationship between dielectric constant andsusceptibility is also available. However, it can be expressed using the formula. So the relationship of the dielectric constant and the dielectric susceptibility has the following entry: e = 1 + X.
With the help of shielding clothing and footwear from matterwith conductive properties, including hats, are used in the energy sector for the safety of personnel performing work in conditions of high tension provoked by high-voltage devices. An electrostatic field does not penetrate inside the conductor, because when a conductor is introduced into an electric field, it will be compensated by a field that arises in connection with the movement of free charges.
This name belongs to substances that haveinsulating qualities. In their composition reside only interconnected charges, and not free. Each positive particle in them will be bonded with a negative inside the atom with a common neutral charge without free movement. They are distributed from inside dielectrics and cannot change their position under the influence of external fields. In this case, the dielectric susceptibility of the substance and the energy received still implies certainchanges in the structure of the substance. The ratio of the positive and negative charges of a particle changes from inside the atom and the molecule, and extra unbalanced interconnected charges appear on the surface of the substance, creating an internal electric field. It is directed towards the tension exerted outside.
This phenomenon is called dielectric polarization.It can be characterized by the fact that an electric field arises from inside the substance, caused by the influence of external energy, but weakened by opposition from the internal field.
Inside dielectrics, it can be represented by two types:
The first type also has an additionalnaming is dipole polarization. This property is inherent in dielectrics with displaced centers of positive and negative charge, which create molecules from small dipoles - the neutral aggregate of a pair of charges. This phenomenon is characteristic of liquids, hydrogen sulphide, carrying nitrogen.
Without influence of an external electric field atOf these substances, molecular dipoles are randomly oriented under the influence of current temperature changes, when on the outside the dielectric does not appear electric charge.
This picture changes under the influence of the attachedoutside the energy when the dipoles do not greatly change their own orientation and uncompensated macroscopic bound charges appear on the surface, creating a field with a direction opposite to the field applied from the outside.
This phenomenon occurs in non-polardielectrics - materials of a different type with molecules in which there is no dipole moment, which under the action of an external field is deformed so that only positive charges are oriented in the direction of the external field vector, and negative charges - in the opposite side.
In total, each molecule functions aselectric dipole oriented along the axis of the applied external field. In a similar way appears on the outer surface of its own field, which has an opposite direction.
These substances change the molecules and the subsequentpolarization from the influence of the field outside is not dependent on their movement under the action of temperature. Methane CH4 can be used as a non-polar dielectric. The numerical indices of the internal field of both dielectrics in magnitude will initially change in proportion to the change in the external field, and after saturation, nonlinear-type effects appear. They appear when each molecular dipole lined up along the lines of force near polar dielectrics, or there were changes in non-polar substances caused by strong deformation of atoms and molecules from a large amount of energy applied outside. In practical cases, this happens very rarely.
Among the insulating materials, a significant role is assigned to electrical indicators and such characteristics as dielectric constant. Both are judged by two different characteristics:
Under the term absolute dielectricThe permeability of a substance is understood as a reference to the mathematical notation of Coulomb's law. With its help, the relationship between the induction vector and intensity is described in the form of a coefficient.
