Dielectric bodies. Active dielectrics What are the names of bodies made of dielectrics?

Conductor- this is a body that contains a sufficient number of free electric charges inside which can move under the influence of an electric field. An electric current may arise in conductors under the influence of an applied electric field. All metals, solutions of salts and acids, moist soil, human and animal bodies are good conductors of electrical charges.

Dielectric or insulator- a body that does not contain free electrical charges inside. Electric current is not possible in insulators.

Dielectrics include glass, plastic, rubber, cardboard, and air. bodies made of dielectrics are called insulators. A completely non-conductive liquid is distilled, i.e. purified water. (any other water (tap or sea) contains some amount of impurities and is a conductor)

Polarization of a dielectric in an electric field- displacement of positive and negative charges in opposite directions, i.e. orientation of molecules.

The physical parameter that characterizes the dielectric is the dielectric constant. Dielectric constant may have dispersion.

Dielectrics include air and other gases, glass, various resins, and certainly dry plastics. Chemically pure water is also a dielectric.

Dielectrics are used not only as insulating materials.

Conductors and insulators differ from each other in how they conduct electricity. Conductors such as copper conduct current easily, but insulators (glass) conduct current only at high voltages. Conductors and insulators are used to control the current. For example, a conductor is used in a lightning rod, causing lightning to strike the ground without causing damage. Insulators are used in switches to protect people.

If a device must conduct current, it contains conductors with low resistance. Most electrical wires are made from metals that conduct current well. Most often, conductors are made of copper; this metal has high conductivity (low resistance).

When current flows through a wire, it encounters resistance. This causes the conductor to heat up. If an electrical device is used as a heater, it contains conductors with high resistance - for example, thin nickel or chrome wire.

The conductivity and resistivity of a wire depend on its thickness. Thin wires have low conductivity (high resistance) compared to thick wires made from the same material.

Thin wires are used in low-voltage networks, for example in telephones. Thicker conductors are designed for higher currents - for example, powering an electric stove.

A dielectric is a material or substance that practically does not allow electric current to pass through. This conductivity is due to the small number of electrons and ions. These particles are formed in a non-conducting material only when high temperature properties are achieved. What a dielectric is will be discussed in this article.

Description

Each electronic or radio conductor, semiconductor or charged dielectric passes electric current through itself, but the peculiarity of the dielectric is that even at high voltages above 550 V, a small current will flow in it. Electric current in a dielectric is the movement of charged particles in a certain direction (can be positive or negative).

Types of currents

The electrical conductivity of dielectrics is based on:

  • Absorption currents are a current that flows in a dielectric at a constant current until it reaches a state of equilibrium, changing direction when turned on and voltage is applied to it and when turned off. With alternating current, the voltage in the dielectric will be present in it the entire time it is in the action of the electric field.
  • Electronic conductivity is the movement of electrons under the influence of a field.
  • Ionic conductivity is the movement of ions. Found in solutions of electrolytes - salts, acids, alkalis, as well as in many dielectrics.
  • Molion electrical conductivity is the movement of charged particles called molions. Found in colloidal systems, emulsions and suspensions. The phenomenon of the movement of molions in an electric field is called electrophoresis.

They are classified according to their state of aggregation and chemical nature. The former are divided into solid, liquid, gaseous and solidifying. Based on their chemical nature, they are divided into organic, inorganic and organoelement materials.

According to the state of aggregation:

  • Electrical conductivity of gases. Gaseous substances have a fairly low current conductivity. It can occur in the presence of free charged particles, which appears due to the influence of external and internal, electronic and ionic factors: X-ray and radioactive radiation, collisions of molecules and charged particles, thermal factors.
  • Electrical conductivity of a liquid dielectric. Dependency factors: molecular structure, temperature, impurities, presence of large charges of electrons and ions. The electrical conductivity of liquid dielectrics largely depends on the presence of moisture and impurities. The conductivity of electricity in polar substances is also created using a liquid with dissociated ions. When comparing polar and non-polar liquids, the former have a clear advantage in conductivity. If you clean a liquid of impurities, this will help reduce its conductive properties. With an increase in conductivity and its temperature, a decrease in its viscosity occurs, leading to an increase in ion mobility.
  • Solid dielectrics. Their electrical conductivity is determined by the movement of charged dielectric particles and impurities. In strong fields of electric current, electrical conductivity is revealed.

Physical properties of dielectrics

When the specific resistance of the material is less than 10-5 Ohm*m, they can be classified as conductors. If more than 108 Ohm*m - to dielectrics. There may be cases when the resistivity will be several times greater than the resistance of the conductor. In the range of 10-5-108 Ohm*m there is a semiconductor. Metal material is an excellent conductor of electric current.

Of the entire periodic table, only 25 elements are classified as non-metals, and 12 of them may have semiconductor properties. But, of course, in addition to the substances in the table, there are many more alloys, compositions or chemical compounds with the properties of a conductor, semiconductor or dielectric. Based on this, it is difficult to draw a definite line between the values ​​of various substances and their resistances. For example, at a reduced temperature factor, a semiconductor will behave like a dielectric.

Application

The use of non-conductive materials is very extensive, because it is one of the most popular classes of electrical components. It has become quite clear that they can be used due to their properties in active and passive form.

In their passive form, the properties of dielectrics are used for use in electrical insulating materials.

In their active form, they are used in ferroelectrics, as well as in materials for laser emitters.

Basic dielectrics

Commonly encountered types include:

  • Glass.
  • Rubber.
  • Oil.
  • Asphalt.
  • Porcelain.
  • Quartz.
  • Air.
  • Diamond.
  • Pure water.
  • Plastic.

What is a liquid dielectric?

Polarization of this type occurs in the field of electric current. Liquid non-conducting substances are used in technology for pouring or impregnating materials. There are 3 classes of liquid dielectrics:

Petroleum oils are slightly viscous and mostly non-polar. They are often used in high-voltage equipment: high-voltage water. is a non-polar dielectric. Cable oil has found application in the impregnation of insulating paper wires with a voltage of up to 40 kV, as well as metal-based coatings with a current of more than 120 kV. Transformer oil has a purer structure than capacitor oil. This type of dielectric is widely used in production, despite the high cost compared to analogue substances and materials.

What is a synthetic dielectric? Currently, it is banned almost everywhere due to its high toxicity, as it is produced on the basis of chlorinated carbon. And the liquid dielectric, which is based on organic silicon, is safe and environmentally friendly. This type does not cause metal rust and has low hygroscopic properties. There is a liquefied dielectric containing an organofluorine compound, which is especially popular due to its non-flammability, thermal properties and oxidative stability.

And the last type is vegetable oils. They are weakly polar dielectrics, these include flax, castor, tung, and hemp. Castor oil is highly hot and is used in paper capacitors. The remaining oils are evaporable. Evaporation in them is not caused by natural evaporation, but by a chemical reaction called polymerization. Actively used in enamels and paints.

Conclusion

The article discussed in detail what a dielectric is. Various types and their properties were mentioned. Of course, in order to understand the subtlety of their characteristics, you will have to study the physics section about them in more depth.

A conductor is a body that contains a sufficient amount of free electrical charges that can move under the influence of an electric field.
An electric current may arise in conductors under the influence of an applied electric field.
All metals, solutions of salts and acids, moist soil, human and animal bodies are good conductors of electrical charges.

An insulator (or dielectric) is a body that does not contain free electrical charges inside.
Electric current is not possible in insulators.
Dielectrics include glass, plastic, rubber, cardboard, and air. bodies made of dielectrics are called insulators.
A completely non-conductive liquid is distilled, i.e. purified water,
(any other water (tap or sea) contains some amount of impurities and is a conductor)

ELECTRIC CURRENT IN METALS

There are always a large number of free electrons in a metal.
Electric current in metal conductors is the ordered movement of free electrons under the influence of an electric field created by a current source.


ELECTRIC CURRENT IN LIQUIDS

Solutions of salts and acids, as well as ordinary water (except distilled) can conduct electric current.
A solution that can conduct electric current is called an electrolyte.
In a solution, the molecules of the solute are converted into positive and negative ions by the action of the solvent. Under the influence of an electric field applied to the solution, ions can move: negative ions - to the positive electrode, positive ions - to the negative electrode.
An electric current occurs in the electrolyte.
When current passes through the electrolyte, pure substances contained in the solution are released on the electrodes. This phenomenon is called electrolysis
As a result of the action of electric current, irreversible chemical changes occur in the electrolyte, and in order to further maintain the electric current, it must be replaced with a new one.

INTERESTING

In the 17th century, after William Gilbert established that many bodies have the ability to become electrified when rubbed, it was believed in science that all bodies with respect to electrification are divided into two types: those capable of being electrified by friction, and bodies that are not electrified by friction. .
It was only in the first half of the 18th century that it was discovered that some bodies also possess the ability to distribute electricity. The first experiments in this direction were carried out by the English physicist Gray. In 1729, Gray discovered the phenomenon of electrical conductivity. He found that electricity can be transmitted from one body to another through a metal wire. Electricity did not spread along the silk thread. It was Gray who divided substances into conductors and non-conductors of electricity. Only in 1739 it was finally established that all bodies should be divided into conductors and dielectrics.
___

By the beginning of the 19th century, it became known that the discharge of electric fish passes through metals, but does not pass through glass and air.


DO YOU KNOW

Galvanostegy.

Coating objects with a layer of metal using electrolysis is called electroplating. Not only metal objects can be metalized, but also wooden objects, plant leaves, lace, and dead insects. First you need to make these objects hard, and to do this, hold them for some time in molten wax.
Then cover them evenly with a layer of graphite (for example, by rubbing with a pencil lead) to make them conductive and lower them as an electrode into a galvanic bath of electrolyte, passing electricity through it for some time. current. After some time, the metal contained in the solution will be released on this electrode and will evenly cover the object.

Archaeological excavations dating back to the times of the Parthian kingdom allow us to assume that already two thousand years ago electroplating of gilding and silvering of products was carried out!
This is also evidenced by finds made in the tombs of Egyptian pharaohs.


EXPERIMENTS WITH ELECTROLYTES

1. If you take a solution of copper sulfate, assemble an electrical circuit and dip the electrodes (graphite rods from a pencil) into the solution, the light bulb will light up. There is current!
Repeat the experiment, replacing the electrode connected to the battery negative with an aluminum button. After some time it will become “golden”, i.e. will be covered with a layer of copper. This is the phenomenon of galvanostegy.

2. We will need: a glass with a strong solution of table salt, a flashlight battery, two pieces of copper wire approximately 10 cm long. Clean the ends of the wire with fine sandpaper. Connect one end of the wire to each pole of the battery. Dip the free ends of the wires into a glass with the solution. Bubbles rise near the lowered ends of the wire!


DO IT YOURSELF!

1. Make a measuring device - a tester to determine whether a substance is a conductor of electric current. To do this, you need a battery, a flashlight lamp and connecting wires. Close the assembled electrical circuit to the conductor under study and determine whether the substance is a conductor by the presence or absence of the lamp glow.

2. You can demonstrate the presence of free electric charges in a liquid like this: connect a metal kettle and an aluminum glass from a calorimeter with conductors to a galvanometer. Pour water into the kettle and dissolve a little salt in it. Start pouring salt water from the kettle into the glass in a thin stream; the galvanometer will show the presence of electric current. By changing the length and thickness of the jet, monitor the change in current strength.


When installing grounding, it is good to bury the wire to a depth of up to 2.5 m. However, in field conditions
this is not always possible. Therefore, grounding is often done in the form of a pin driven into the ground. Why is it useful to water the grounding area with salt water in this case?


NO-I-I!

If a fire occurs in electrical installations, you must immediately turn off the switch. Fire caused by electric current CANNOT be extinguished with water or a regular fire extinguisher, because the stream of water is a conductor and can close the circuit again and restore the cause of the fire. In this case, it is necessary to use dry sand or a sandblasting fire extinguisher.


THE HUMAN BODY IS A CONDUCTOR OF ELECTRICITY

If a person accidentally becomes energized, injury or even death may occur.

When working with electrical circuits, DO NOT:
- You cannot touch bare wires with both hands at the same time.
- do not touch a bare wire while standing on the ground or on a damp (even cement or wooden) floor.
- Do not use faulty electrical appliances.
- you cannot repair an electrical device without disconnecting it from the power source.

First aid for an electric shock victim.

Often the person himself cannot free himself from current-carrying wires, because... The electric current causes convulsive muscle contractions, or the victim loses consciousness. First you need to disconnect the person from the current-carrying wires. To do this, you need to turn off the current or unscrew the fuses located near the meter. If the switch is far away, then you need to use a wooden stick (non-conductive object) to pull it away from the wire. There should be an insulating surface under your feet: a rubber mat, dry boards or linoleum. You can only pull the victim away from the wires with your bare hands by the ends of dry clothing and with one hand. Do not touch those connected to the ground. conductive objects!
Then the victim should be placed on his back and a doctor should be called.

Don't stick your fingers into the socket, they will come in handy later!

DEFINITION, PURPOSE AND CLASSIFICATION

ELECTRICAL INSULATING MATERIALS

Dielectrics- substances in which electrostatic fields can exist for a long time. These materials, in contrast to conductive ones, practically do not conduct electric current under the influence of a constant voltage applied to them.

The purpose of electrical insulation is primarily to prevent the passage of current along paths undesirable for the operation of an electrical device. In addition, dielectrics in electrical devices, in particular capacitors, play an active role, providing the required capacitance.

Dipole dielectrics are those whose molecules are arranged asymmetrically in space; they generally have a higher dielectric constant than neutral dielectrics. Dipole dielectrics are more hygroscopic and are more easily wetted by water than neutral ones.

Dielectrics are also divided into heteropolar (ionic), whose molecules are relatively easily split into oppositely charged parts (ions), and homeopolar, not split into ions.

Based on their chemical composition, electrical insulating materials are divided into organic, V whose composition includes carbon, and inorganic, containing no carbon. Usually, inorganic materials have higher heat resistance, than organic.

ELECTRICAL CONDUCTIVITY OF DIELECTRICS

By their very purpose, dielectrics under the influence of constant voltage should not allow current to pass at all, i.e. they should be non-conductors. However, all practically used electrical insulating materials, when applying a constant voltage, pass some insignificant current, the so-called leakage current. Thus, the resistivity of electrical insulating materials is not infinite, although it is very large.

Resistance section of insulation is equal to the ratio of the DC voltage applied to this section of insulation U (in volts) to leakage current I(in amperes) through this section:

Conductivity of insulation

.

Distinguish volumetric resistance isolation R V , numerically determining the obstacle created by the insulation to the passage of current through its thickness, and surface resistanceR S defining an obstacle to the passage of current along the insulation surface and characterizing the presence of increased conductivity of the surface layer of the dielectric due to moisture, contamination, etc.

Impedance insulation is defined as the result of two resistances connected in parallel between the electrodes, volume and surface:

For a flat section of insulation with a cross section S[cm 2 ] and thickness h[cm] volumetric resistance (excluding the influence of edges) is equal to:

.

Numerically ρ V equal to the resistance (in Ohms) of a cube with an edge of 1 cm of a given material, if the current passes through two opposite faces of the cube:

.

1 Ohm∙cm= 10 4 Ohm∙mm 2 /m= 10 6 μΩ∙cm= 10 -2 Ohm∙m.

The reciprocal of volumetric resistivity

,

called specific volume conductivity material.

Values ρ V practically used solid and liquid electrical insulating materials range from approximately 10 8 -10 10 Ohm∙cm for relatively low-quality materials used in unimportant cases (wood, marble, asbestos cement, etc.) up to 10 16 -10 18 Ohm∙cm for materials such as amber, polystyrene, polyethylene, etc. For non-ionized gases ρ V about 10 19 -10 20 Ohm∙cm The ratio of the resistivity of a high-quality solid dielectric and a good conductor (at normal temperature) is expressed by a colossal number - on the order of 10 22 -10 24.

Specific surface resistanceρ S characterizes the property of an electrical insulating material to create surface resistance in the insulation made from it. Surface resistance (neglecting the influence of edges) between electrodes with straight edges parallel to each other of length b, located at a distance from each other A, when excluding the volumetric leakage current through the thickness of the material, it is equal to , Where .

Magnitude ρ S numerically equal to the resistance of a square (of any size) on the surface of a given material , if the current is supplied to the electrodes limiting the two opposite sides of this square .

Physical nature of electrical conductivity of dielectrics

The electrical conductivity of dielectrics is explained by the presence in them of free (i.e., not associated with certain molecules and able to move under the influence of an applied electric field) charged particles: ions, molions (colloidal particles), and sometimes electrons.

Most typical for most electrical insulating materials ionic conductivity. It should be noted that in some cases the main substance of the dielectric is subjected to electrolysis; An example is glass, in which, due to its transparency, the release of electrolysis products can be directly observed. When direct current is passed through glass, heated to reduce conductivity, characteristic tree-like deposits (“dendrites”) of the metals that make up the glass, primarily sodium, form at the cathode. Even more often, cases are observed when the molecules of the main substance of the dielectric do not have the ability to be easily ionized, but ionic electrical conductivity occurs due to impurities almost inevitably present in the dielectric - impurities of moisture, salts, acids, alkalis, etc. Even very small ones, sometimes with impurities that are difficult to detect by chemical analysis can significantly affect the conductivity of a substance; Therefore, in the manufacture of dielectrics and in general in electrical insulation technology, the purity of the starting products and the cleanliness of the workplace are so important. In a dielectric with an ionic conductivity, Faraday's law is strictly observed, i.e., the proportionality between the amount of electricity passed through the insulation (at constant current) and the amount of substance released during electrolysis.

When increasing temperature The resistivity of electrical insulating materials, as a rule, is greatly reduced. Obviously, the operating conditions of electrical insulation become more severe. At low temperatures, on the contrary, even very poor dielectrics acquire high values ρ V .

The presence of even small amounts of water can significantly reduce ρ V dielectric. This is explained by the fact that impurities present in water dissociate into ions, or the presence of water can contribute to the dissociation of the molecules of the substance itself. Thus, the operating conditions of electrical insulation become more difficult when hydration. Humidification has a very strong effect on the change ρ V fibrous and some other materials in which moisture can form continuous films along the fibers - “bridges” that penetrate the entire dielectric from one electrode to another.

To protect against moisture after drying, hygroscopic materials are impregnated or coated with non-hygroscopic varnishes, compounds, etc. When drying electrical insulation, moisture is removed from it, and its resistance increases. Therefore, as the temperature increases ρ V moistened material may even grow at first (if the effect of moisture removal outweighs the effect of increasing temperature), and only after removing a significant part of the moisture does a decrease begin ρ V .

Insulation resistance may decrease with increase in voltage, which has significant practical significance: by measuring the insulation resistance (of a machine, cable, capacitor, etc.) at a voltage that is lower than the operating voltage, we can obtain an overestimated resistance value.

Addiction R from on the voltage value is explained by a number of reasons:

    formation of space charges in the dielectric;

    poor contact between the electrodes and the measured insulation, etc.

At sufficiently high voltages, electrons can be released by electric field forces; the additional electronic conductivity created in this case leads to a significant increase in the overall electrical conductivity. This phenomenon precedes the development of dielectric breakdown.

When a constant voltage is applied to a solid dielectric, in most cases the current gradually decreases over time, asymptotically approaching a certain steady-state value. Thus, gradually the conductivity of the dielectric increases and the resistance decreases. The change in conductivity over time is associated with the influence of the formation of space charges, with electrolysis processes in the dielectric and other reasons.

Character of changes in specific surface resistance ρ S dielectrics from various factors (temperature, humidity, voltage, time of exposure to voltage) is similar to the nature of the change ρ V discussed above. Magnitude ρ S hygroscopic dielectrics are very sensitive to moisture.

Polarization of dielectrics

The most important property of dielectrics is their ability to polarize under the influence of externally applied electrical voltage. Polarization comes down to a change in the spatial position of charged material particles of a dielectric, and the dielectric acquires induced electric torque, and an electric charge is formed in it. If we consider some section of insulation with electrodes to which voltage is applied U [V], then the charge of this section Q [Cl] is determined by the expression

Q= C.U. .

Here WITH is the capacitance of a given section of insulation, measured in farads (f).

The insulation capacity depends both on the material (dielectric) and on the geometric dimensions and configuration of the insulation.

The ability of a given dielectric to form electrical capacitance is called its dielectric constant and is designated ε . Magnitude ε vacuum is taken as one.

Let WITH O- capacity of a vacuum capacitor of arbitrary shape and size. If, without changing the size, shape and relative position of the capacitor plates, the space between its plates is filled with a material with a dielectric constant ε , then the capacitance of the capacitor will increase and reach the value

C=ε C O .

Thus, the dielectric constant of a substance is a number showing how many times the capacity of a vacuum capacitor will increase if, without changing the size and shape of the capacitor electrodes, the space between the electrodes is filled with a given substance. The capacitance of a capacitor of given geometric dimensions and shape is directly proportional ε dielectric.

The value of dielectric constant is included in many basic equations of electrostatics. Yes, according to the law pendant force of mutual repulsion of two point electric charges of magnitude Q 1 and Q 2 (absolute charge units) located in a medium with dielectric constant ε at a distance from each other h[cm] , is:

Dielectric constant is a dimensionless quantity. For gases it is very close to 1. So, for air under normal conditions ε= 1.00058. For most liquid and solid electrical insulating materials ε – on the order of several units, less often tens and very rarely exceeds 100. Some substances of a special class - ferroelectrics - under certain conditions have exceptionally high values ​​of dielectric constant.

The physical essence of polarization

Polarization, like conductivity, is caused by the movement of electrical charges in space. The differences between these two phenomena:

    polarization causes a shift related with certain molecules of charges that cannot go beyond the boundaries of a given molecule, while conductivity is due to the movement (drift) of free charges that can move in a dielectric over a relatively large distance;

    polarization displacement – ​​elastic shift of charges;

    polarization of a homogeneous material occurs in almost all dielectric molecules, while the electrical conductivity of dielectrics is often determined by the presence of a small amount of impurities (contaminants).

While the conduction current exists as long as a constant voltage is applied to the dielectric from the outside, bias current (capacitive current) occurs only when the direct voltage is turned on or off, or even when the magnitude of the applied voltage changes; for a long time there is a capacitive current only in the dielectric under the influence alternating voltage.

The most typical types of polarization are electronic, ionic and dipole.

Electronic polarization- displacement of electron orbits relative to the atomic nucleus. Electronic polarization when an external electric field is applied occurs in an extremely short time (about 10 -15 sec).

Ionic polarization(for ionic dielectrics) - the displacement relative to each other of the ions that make up the molecule. This polarization occurs in periods longer than electronic polarization, but also in very short periods - about 10 -13 seconds.

Electronic and ion polarization - varieties deformation polarization, representing a shift of charges relative to each other in the direction of the external electric field.

Dipole (orientation) polarization comes down to the rotation (orientation) of dipole molecules of a substance. This polarization is numerically large compared to deformation polarization and occurs completely over time intervals that are different for molecules of different substances, but significantly longer than the duration of deformation polarization.

It is obvious that in neutral dielectrics only deformation polarization can occur. These dielectrics have a relatively low dielectric constant (for example, for liquid and solid hydrocarbons ε about 1.9-2.8).

Table 1.1

The dielectric constant of some substances

Dipole dielectrics, in which, in addition to deformation polarization, orientation polarization is also observed, have higher values ​​of dielectric constant compared to neutral dielectrics, and in dipole dielectrics, for example, for water, ε = 82.

The dielectric constant of a dipole substance, generally speaking, is greater, the smaller the size of the molecule (or molecular weight). Yes, quite big ε water is due to the very small size of its molecule.

Dependence of dielectric constant on frequency. Since the time of establishment of deformation polarization is very short compared to the time of change in the sign of the voltage even at the highest frequencies used in modern radio electronics, the polarization of neutral dielectrics manages to be fully established in a time that can be neglected in comparison with the half-cycle of an alternating voltage. Therefore, there is practically no significant dependence ε from frequency neutral dielectrics do not.

For dipole dielectrics, as the frequency of the alternating voltage increases, the value ε at first also remains unchanged, but starting from a certain critical frequency, when the polarization does not have time to fully establish itself in one half-cycle, ε begins to decrease, approaching at very high frequencies the values ​​characteristic of neutral dielectrics; As the temperature increases, the critical frequency increases.

In sharply inhomogeneous dielectrics, in particular, in dielectrics with inclusions of water, the phenomenon of the so-called interlayerNoah polarization. Interlayer polarization is reduced to the accumulation of electric charges at the interfaces between dielectrics (in the case of a moistened dielectric, on the surface of disseminated water). The processes of establishing interlayer polarization are very slow and can take place over minutes and even hours. Therefore, the increase in insulation capacity due to moistening of the latter is greater, the lower the frequency of the alternating voltage applied to the insulation.

HeadThe dependence of dielectric constant on temperature. For neutral dielectrics ε weakly depends on temperature, decreasing as the latter increases due to thermal expansion of the substance, i.e., a decrease in the number of polarizable molecules per unit volume of the substance.

In dipole dielectrics at low temperatures, when the substance has high viscosity, the orientation of dipole molecules along the field is in most cases impossible or, in any case, difficult. As the temperature increases and the viscosity decreases, the possibility of dipole orientation becomes easier, resulting in ε increases significantly. At high temperatures, due to increased thermal chaotic thermal vibrations of molecules, the degree of orderliness of molecular orientation decreases, which again leads to a decrease ε .

In crystals with ionic polarization, glasses, porcelain and other types of ceramics with a high content of the glassy phase, the dielectric constant increases with increasing temperature.

DIELECTRIC BODIES

DIELECTRIC BODIES

Otherwise, insulators, i.e. bodies that do not conduct electricity, are not a conductor.

A complete dictionary of foreign words that have come into use in the Russian language. - Popov M., 1907 .

DIELECTRIC BODIES

non-conducting electricity, insulators.

, 1907 .

INSULATORS OR DIELECTRIC BODIES

in general, all bodies that conduct electricity poorly and serve to insulate conductors; in particular, this name refers to glass or porcelain glasses, used. on a telegraph line to insulate the wire at the points where it is attached to the poles.

Dictionary of foreign words included in the Russian language. - Pavlenkov F., 1907 .


See what "DIELECTRIC BODIES" are in other dictionaries:

    The name given by Michael Faraday to bodies that do not conduct, or, otherwise, poorly conduct electricity, such as air, glass, various resins, sulfur, etc. Such bodies are also called insulators. Before Faraday's research, carried out in the 30s... ...

    The name given by Michael Faraday to bodies that are non-conducting or, in other words, poorly conducting electricity, such as air, glass, various resins, sulfur, etc. Such bodies are also called insulators. Before Faraday's research in the 1930s... ... Encyclopedia of Brockhaus and Efron

    Poor conductors of electricity and therefore used to insulate conductors. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. INSULATORS OR DIELECTRIC BODIES in general, all bodies that are poorly conductive... ... Dictionary of foreign words of the Russian language

    Substances that do not conduct electricity well. The term "D." (from the Greek diá through and English electric electric) was introduced by M. Faraday (See Faraday) to designate substances through which electric fields penetrate. In any substance... ... Great Soviet Encyclopedia

    ULTRA-SHORT WAVES- were first used in Schliephake therapy. Alternating currents used in diathermy are characterized by a frequency of 800,000 to 1 million oscillations per second with a wavelength of 300,400 m. In the crust, currents with a frequency of 10 ... Great Medical Encyclopedia

    electric- 3.45 electric [electronic, programmable electronic]; E/E/PE (electrical/electronic/programmable electronic; E/E/PE) based on electrical and/or electronic and/or programmable electronic technology. Source … Dictionary-reference book of terms of normative and technical documentation

    Encyclopedic Dictionary F.A. Brockhaus and I.A. Ephron

    One of the branches of the study of electrical phenomena, which includes the study of the distribution of electricity, subject to its equilibrium, on bodies and the determination of those electrical forces that arise in this case. The foundation of E. was laid by the work... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Ephron

    Classical electrodynamics ... Wikipedia

    Classical electrodynamics Magnetic field of a solenoid Electricity Magnetism Electrostatics Coulomb's Law ... Wikipedia

Books

  • Fundamental principles of chemical deposition processes of films and structures for nanoelectronics, Team of authors, The monograph presents the results of the development of processes of chemical vapor deposition of metal and dielectric films using non-traditional volatile starting materials... Category: Technical literature Series: Integration projects of the SB RAS Publisher: Federal State Unitary Enterprise "Publishing House SB RAS", eBook(fb2, fb3, epub, mobi, pdf, html, pdb, lit, doc, rtf, txt)
  • Solid State Physics for Engineers Textbook, Gurtov V., Osaulenko R., The textbook is a systematic and accessible presentation of the course in solid state physics, containing the basic elements of condensed matter physics and its applications for... Category: