The space around any electrical charge or several charges through which the interaction is carried out between charges, is called electric field .

The electrical field is one of the sides of the electromagnetic field, which is a special kind of matter and is characterized by the following properties:

1. The electromagnetic field exists around any charged particle or body.

2. The field is characterized by a continuous distribution in space.

It has a mass.

The field is a carrier of energy.

The field energy can be transformed into other types of energy (mechanical, chemical, etc.)

The electric field is characterized by the following values:

tension;

potential;

voltage.

Tension electric field At this point, the value is numerically equal to the power with which the field is valid for a single point chargeplaced at this field point:

Tension is a vector value. For the direction of tension vector, the direction of force is taken from which the field acts on a positive charge placed at this field.

El. The field can be depicted using email. silest lines So that the tensions vector are directed by the tangent of El. Power lines.

El. Power lines are the paths for which a positive charge is moved under the action of the field.

With the help of email The power lines can be shown the intensity of the field, while the line is carried out through the platform, the number of which is proportional to the field strength. If in the tension formula substitute the value of force F.from the law of Kulon, we will get:

If the field is created by several point charges, the intensity of such a field is defined as the geometric sum of the tensions created by each charge separately.

If the angle is not direct, then use the cosine theorem.

Electric voltage call the attitude of the work performed by the field for the movement of the test charge from one point of the field to another, to the magnitude of this charge.

El. The field may be homogeneous and inhomogeneous. In a homogeneous field of tension of the same in size and direction.

The electrical voltage is the energy characteristic of the field. This is a scalar value.

Electric potential at this point, the value is numerically equal to the operation spent on moving a single point (positive) charge due to the field of the field at this point.

The potential is a scalar value, it can be positive and negative.

For comparison of potentials, a conditional concept zero potential.It is conventionally believed that the zero potential has the surface of the Earth, and if the potential is above zero, then it is positive, and if it is negative below.

The potential difference between the two points of EL. Fields call voltage between these points:

Communication between the voltage and tension of EL. Fields are defined as follows. Work on moving a test charge in email. The field can be determined:

A task

Conductors of the first row: all metals and their alloys. Second row conductors: electrolytes.

Dielectrics: ceramics, glass, mica, quartz, asbestos, plastics, rubber, mineral oils, varnishes, air, etc.

Shifted with each other under the action of an external email. Fields and at the same time associated charged particles within the molecule form dipole .

This phenomenon is called polarization of dielectric . If the dielectric is removed from the external email. Fields, the polarization is completely stopped. But some dielectrics (titanate barium, lead titanate) with the disappearance of the field retain residual polarization.

Email tension The fields at which the sample of the dielectric occurs, is called el. Dielectric strength , or publishing tension .

The voltage at which the sample of the dielectric is called punch voltage.

Attitude

called flavor of strength .

Semiconductors occupy an average position in conductivity between metals and dielectrics. With an increase in temperature, their conductivity increases. These include: silicon, germanium, selenium, copper, sulfur lead, etc.

What is called electric field strength? What formula expresses the essence of this concept? Electric field tension - power characteristic field physical quantityequal to the ratio of power acting on the point placed at this point electric charge, To this charge.

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Electrostatics

"Static electricity" - in the warm season, try to go barefoot as much as possible, especially in wet earth. Clothing. If possible, give up synthetics, wear linen and cotton and wool clothing. Throughout the Millennium, our ancestors went on earth barefoot, grounding naturally. Excess electricity must be derived from the body to the grounding method.

"Elementary particles" - introduction to electrodynamics. Electrodynamics - section of physics studying the interaction of electrical charges. The main action of the electric field is the acceleration of bodies or particles with an electric charge. The electromagnetic field is a combination of electrical and magnetic fields that can move into each other.

"Elektroscope" is a question. Electric charge. Electroscope rod. Electroscope. Get acquainted with the device of the electroscope. Ebonite sticks. Force. Body. Type of matter. Act. The interaction of charges. Two types of charges. Charged dust. Conductors and dielectrics. Rubber sticks.

"Basics of electrostatics" - the law of saving charge. Field strength inside conductive ball. Electrical charges. Electric field strength. Tension. Uniform work electrostatic field. Potential point. Particles. [U] \u003d B - voltage. Electrification tel. Principle of superposition of fields. Potential. Electric field.

"Electrification" - explain in more detail. Paints are consumed significantly less. Why attach a metal chain to the tank, which concerns the Earth? Woolen cloth. Planmarks of a flat capacitor. How do free electrons move in plates in the absence of an electric field? Electride clothing made of synthetic fabrics, polymer and carpeted floors.

"Physics" Electrostatics "" - the law of Kulon. Electrification phenomenon. Test tasks. Electrification. Calculations. What is called electric field strength lines. Is it possible to share the electric charge infinitely. Proportionality coefficient. What interactions are called electromagnetic. Square root. Solving key tasks.

Total in the subject of 14 presentations

We live in the ocean of magnetic and electric fields. Like the behavior of the ocean in the calm, these fields may be more and less stable, turning into a storm in real storms.

From childhood, we know the property of the compass magnetic arrows to point to the north under the action of permanent geo magnetic field Earth. At one time, the invention of the compass played a huge role in the history of mankind, especially with the development of navigation.

Unlike the magnetic field, the electric field of the Earth does not exhibit itself in everyday life, and we cannot identify it without special devices. Although sometimes we observe the manifestation of the electric field, calculating the washed and dried hair of plastic calcination or by conducting the same calculation over the slices of cellophane or paper, which, overcoming the earth's attraction, bounce from the table, sticking to the calcination.

But it is worth come the electric bora, as we feel it approaching without any devices. We see the spilos of the distant garnings of the approaching thunderstorm, and hear distant rollers. There are interference when receiving radio and television signals; Lightning discharges can outrue radio and electronic equipment, communication lines and power lines.

An example is the power supply accident in New York in 1977, when, after a series of lightning in various power lines, almost the entire octalillion city remained without power supply. Geomagnetic cosmic scale storms can also lead to accidents in the power supply of cities and countries (Quebec accident in 1989), or cause interruptions in telegraph communications on the entire continents (Crawon Event in 1859). At the same time, the perturbation of the magnetic field on the surface of the Earth during the geomagnetic storms constitute an average of less than 1% of the values \u200b\u200bof stationary value.

According to modern ideas, individual-changing electric and magnetic fields form uniform electromagnetic fields, varying with a smaller or greater frequency. Their spectrum is extremely wide - from the infusion frequencies in the share of Hertz to the gamma-radiation quantums with a frequency in Exager.

Curious, but a little-known fact: in a narrow spectrum radio view on which television broadcasting is being conducted and communication satellites operate, the power of the radiated land signal exceeds the power of the radiation of the Sun! Some radio astronomers offer to search for extraterrestrial civilizations comparable to our civilization, on this basis. True, other scientists consider it simply a sign of our technological backwardness and inability to intelligently dispose of energy resources.

The most important characteristic of the electric (as well as the magnetic) field is its tension. Excess this parameter is above a certain value for this medium (for air it is 30 kV / cm) leads to an electric breakdown - an intertarious discharge. In our lighters, the discharge power is so small that its energy is enough only to heat the gas to the temperature of the ignition.

The power of a separate zipper with average voltage values \u200b\u200bof 20 million volts and current of 20 thousand amps can be 200 million kilowatts (given that when the lightning discharge, the voltage drops from the maximum value to zero). And for one powerful thunderstorm, the same energy is distinguished as the entire US population consumes in 20 minutes.

Considering the fact that more than 2000 thunderstorms threaten on Earth every month simultaneously, the development of atmospheric electricity energy seems extremely tempting. There are many projects for the interception of lightning with special bulbs or initialization of the discharge of lightning; In this regard, we already have technologies that allow you to cause a discharge of a launch of small missiles or air chambers associated with conductors with the surface of the Earth. More promising, developments based on the ionization of the atmosphere of the rays of powerful lasers or microwave radiation and the creation of thus conductive channels for the discharge of lightning, which makes it possible to eliminate the need for material costs associated with evaporation of conductors after a lightning strike.

In essence, we do not need to generate actual electricity - it remains only to organize it with the reception, storage and transformation into a more convenient form for practical purposes - but while this task is assigned to future technologies and devices. The possible solution of problems can be new materials like graphene, and superconductors, or the creation of ionistors with an incredibly high density of poisonable energy.

And the dream of genius from electricity - American Serbian origin Nikola Tesla will be carried out; And we will be able to convert the energy of thunderstorms into a single energy field, which will allow to receive electricity in the required quantity anywhere in the land and even in its atmosphere. After all, it was possible during the experiments to obtain artificial lightning in June 1889 in its laboratory located in Colorado Springs, achieve such a transfer electrical power Without wires that horses in the district rolled down, having received an electric blow through metal horseshoes! Butterflies flew in the halo of the lights of St. Elma, the sparks slipped between the feet of pedestrians, the same sparks were poured from water taps. Maybe because of such experiences, many contemporaries considered Tesla just a dangerous madman.

But, they say that if you are ahead of mankind one step - you are exactly a genius! But if two steps are you mad!

Historical reference

The concept of electric field strength is directly related to the concept of electrical charges and the electric fields created by these charges.

Open French scientist chall pendant In 1785, the law of interaction of electrical charges only gave a tool into physicists to calculate the interaction as such. This law was amazingly similar to the law of World Newton's law, which was revealed earlier, although he had a significant difference: he admitted charges of different signs, and only one sign in the law of world community has only one sign, i.e. Material bodies could only attract.

Like Newton, who did not reveal the causes of gravitational interaction, the pendant was also unable to clarify the reasons for the interaction of electrical charges.

The best minds of that time were offered various theories origin of these forces, their number included the theories of closesthoods and long-range effects. The first assumed the presence of a certain intermediate agent - global ether with completely exotic properties. For example, he was attributed to huge elasticity with insignificant density and viscosity. This was due to the prevailing science of the science of mechanistic ideas about the transmission medium as a certain fluid. The controversial results of experiments on the study of the properties of the ether were finally buried in the 20th century as a result of the experiments of the American physics of Alberta Michelson and special theory The relativity of Albert Einstein.

A breakthrough in this direction was made by outstanding English physicists Michael Faraday and James Clerk Maxwell at the end of the 19th century. M. Faraday managed to connect magnetic and electrical fields by introducing the concept physical field And even visualize it with the help of "electric power lines". In modern physics for the image of vector fields, the strength lines of the vector field are used.

Just as we can visualize the power lines of the magnetic field, placing small iron sawdust in the magnet field, Faraday visualized the spread of the electric field, placing the crystalline of the Kinin dielectric in a viscous liquid - castor oil. At the same time, close to the charged bodies, crystalline were built into the chains of a bizarre form depending on the distribution of charges.

But the main merit of Faraday is that he has introduced a concept that electrical charges do not act directly. Each of them creates electric and magnetic in the surrounding space (if it moves) the field, and the manifestation of electromagnetic effects essence is a simple change in the amount of power lines covered by some contour.

Under the number of power lines, he meant the tension of an electric or magnetic field.

The great compatriot Faraday J. K. Maxwell managed to give his ideas quantitative mathematical form, so necessary in physics. Its system of equations has become a basis for studying both theoretical and practical sides of electrodynamics. The work of Maxwell put the cross on the concept of long-range: the fundamental result obtained by them predicted the final propagation rate of electromagnetic interactions in vacuo.

Later, this postulate on the limb of the speed of the spread of light, as an electromagnetic interaction, was put on the genius physicist of the 20th century by Albert Einstein as a fundamental postulate of his special (service station) and general (OTO) theories of relativity.

In modern physics, a somewhat different meaning is invested in the concepts of long-range effects: the forces decreasing with the distance under the laws of the reverse degree (R -n) are considered long-range; These include gravitational and Coulomb interactions, decreasing in proportion to the reverse square of the distance and valid between objects in the usual world.

In the atomic world there are other forces, rapidly decreasing with distance: they include strong and weak interactions. These forces act between the micromir objects.

Electric field strength. Definition

The tension of the electric field is a vector physical quantity characterizing the electric field at a given point and numerically equal to the ratio of the amount of force acting on the fixed point electrical charge, placed at this point, to the size of the charge. It is indicated by the Latin letter E. (pronounced as vector E) and is calculated on the basis of the formula:

E. = F./q.

where E. - vector electric field strength, F. - Vector forces acting on the point charge, Q - the charge of the object.

At each point of the space, there is its value of the intensity vector, since the field may vary over time, therefore, as an argument, the function describing this vector voltage field includes not only spatial coordinates, but also time.

E. = f. (x, Y, Z, T)

The voltage of the electric field in the international system of SI units is measured in volts per meter (in / m) or Newton on a pendant (N / CL).

In addition to the main unit of the voltage of the electric field, a dollar unit (V / cm) is used, multiple units (kV / m or kV / cm) are used in the electrical engineering.

In countries where metric units of lengths are not used, the electric field strength is measured in volts per inch (in / inch).

Electric field strength. Physics phenomena

As already mentioned above, the calculations of the vector electric fields (field tension) of physical objects are carried out using Maxwell Elektrostatics equations and the Gauss-Ostrogradsky theorem, as an integral part of the General Equations of Maxwell.

At the same time, it is necessary to take into account the peculiarities of the behavior of electric fields in various media, since their manifestations are dramatically distinguished depending on the specific state of the substance relative to the electrical conductivity.

Features of the manifestation of the electric field in dielectrics

When the high voltage electric field is supplied to the sample from a solid dielectric, in the latter, as a rule, it is reorienting the chaotic polar molecules in the direction of the electric field. This phenomenon is called polarization. Even when removing the electric field, this orientation is saved. To resolve it requires an applied field of the back.

This phenomenon is called the dielectric hysteresis. Return to the initial state of the dielectric can also be facilitated by other methods of physical effects on the sample, most often used simple heating, and the phase transition of the dielectric is also occurred in its original state.

Such materials were called ferroelectrics or ferroelectrics. Among them, a special class can be distinguished by substances that have a very wide loop of dielectric hysteresis and be in a polarized state for a long time - they are called electrically, in fact, play the role of permanent magnets in electrical execution, creating a constant electric field.

It should be noted that the name "ferroelectric" is in no way connected with the hardware; It appeared due to the fact that the phenomenon of ferroelectricity is similar to the phenomenon of ferromagnetism. In English, the phenomenon of ferroelectricity is called: Ferroelectricity.

Under the action of an alternating electric field, the dielectric molecule behave somewhat differently, constantly changing the spatial orientation of the charges of the attached fields inherent in the charges. The understanding of these processes laid the British scientist J. K. Maxwell, who introduced the concept of displacement currents in the use of science science.

The essence of the phenomenon is that under the action alternating current related charges - electrons and kernels - in dielectric molecules fluctuate relative to the center of the molecule, reacting to the applied alternating electric field.

Features of the manifestation of the electric field on the surface of the metals

Completely different is the interaction of the electric field with metals. Due to the presence of free charges (electrons) in them with respect to any electrical or electromagnetic field, they behave like an optical mirror against light.

In this principle, many directed antennas were built for receiving radio signals - regardless of the specific design of the antenna, they necessarily contain one element - the reflector (or deflector), which allows to significantly increase the received radio signal and thereby improve the quality of reception. It may look completely different, up to a complete analogue of an ordinary mirror in the form of parabolic reflectors antennas for receiving satellite signals. In essence, the deflector is just a voltage concentrator. electromagnetic field.

Since the metals reflect electrical and electromagnetic fields, the electrostatic protection cell is constructed in the same principle - the so-called cell or Faraday shield - the metals are completely insulates the space in them from the effect of electric, and the electromagnetic field. This perfectly knew the genius of electricity Nikola Tesla, and hit the unenmended public with the appearance of electrical discharges created by its resonant transformer in such a cell. Now we call it a transformer (or coil) of the Tesla.

In 1997, the physicist from California Austin Richards created a flexible costume of electrostatic protection, which defended him from the discharges of the Tesla coil, and since 1998 he opposes the world under the pseudonym Dr. Megavolt in the show "Blowing Man".

By the way, modern premises for hidden negotiations are made on the same principle of Faraday cells; True, the inventors from the closed research institutes of the KGB of the USSR were able to circumvent American engineers at one time during the construction of the US Embassy: listening devices were embedded in the form of isolated structures in the bearing walls of the building. It was assumed that under the action of external irradiation, they would generate a response industrial signal, and to issue the secrets of negotiations of American diplomats.

Practical examples of devices and installations using an electric field

There are many examples of both the use of the electric field and to combat it.

Scanning tunnel microscope

One of the principles of operation of the scanning tunnel microscope (STM) is the creation of such an electric field strength between the studied sample and the sharp needle probe so that it exceeds the operation of the electron output from the sample. This is achieved by the application of a small potential difference between the sample and the probe, and their convergence of less than one nanometer. Then, moving the probe above the surface, by measuring the flowing tunnel current, you can get the profiles of the sample and build an image of its surface.

Given the sensitivity of the device to mechanical vibrations, to the premises in which the STM are placed, special requirements are presented: in particular, the surfaces of the walls, the ceilings and flooring of the rooms are equipped with acoustic protection absorbing sound oscillations.

Measuring instruments and alert instruments

According to the requirements of labor protection, the premises are classified by the level of electric field strength. Depending on this level, the residence time of the technical personnel in such premises is strictly regulated. Stroy measurements are made by special devices.

Meteocentra different countries Control the electric field of the Earth, measuring its tension both on the surface and in various layers of the atmosphere with high-rise probes.

Electromontors of installations and high voltage lines for signaling about a dangerous convergence with current-carrying parts that are under voltage, use alert instruments that measure the voltage of the electric field.

Electrostatic and electromagnetic protection

Farmadium itself, when carrying out chemical experiments, to eliminate the influence of third-party electric fields to the results of experiments, an electrostatic protection device, known as the Faraday cell, was applied in 1836. It can be made in the form of a solid conductive shell with holes or in the form of a grid of conductive materials.

The same device can be successfully used to shield electromagnetic radiation with a wavelength, significantly higher than the size of the mesh cells or holes.

In modern technology, Faraday cells are equipped with physical laboratories and installations, laboratories of analytical chemistry and measuring equipment, premises for secret negotiations and even premises for a meeting of the Cardinalov Conclave, at which the last election of the Pope of Roman.

Since physical research methods are widely used in modern medicine, the premises of the diagnostic centers are also equipped with Faraday cells - the examples can serve as an example, in which magnetic resonance tomography is carried out.

Even in the usual home-made microwave furnace, the heating chamber is structurally made in the form of a Faraday cell, and an optically transparent window in it, made by special technology, is not transparent for microwave emissions.

Screens of connecting wires and coaxial cables, widely used in radio engineering, computer technology and communication techniques to protect against external electromagnetic radiation and radiation of the inner signal into an external environment, are also peculiar Faraday cells.

Experiments on the effects of electric fields on metals and gases

Not connected thin fluorescent lamps from a flat display can be lit with a plasma lamp If you touch the surface of the plasma lamp with your fingers, there is a concentration of plasma cords.

If you bring the indicator lamp (even faulty, but with a whole cylinder) to the insulating sphere of the plasma lamp, it will start glowing, registering the presence of a field.

It is obvious that the electromagnetic field penetrates through the glass shells of both lamps, the field excites the electrons of the upper shells of the gas atoms, the latter during return to the initial state generate light.

If you bring a hand to the surface of the lamp, then you can observe the thickening of the plasma cord, as we create an increased voltage of the electric field at the point of contact.

Evaluation of the voltage of the electric field using an oscilloscope

Connect to the input of the oscilloscope the probe made from a piece of wire with a length of about 15 cm, and bring it to the Tesla lamp. On the oscilloscope screen, we observe induced oscillations with the same frequency of 25 kHz and 25 volts. A variable voltage is supplied to the lamp electrode, which generates an alternating electric field in space. By increasing the distance between the lamp and the wire, we will observe a decrease in the scope of the signal (Fig. 1-3). By reducing the amplitude of the signal on an oscilloscope, it can be concluded that the field strength decreases with distance.

Screening of electromagnetic field

Connect to the oscilloscope input shielded measuring cable (Fig. 4). In this case, the signal registered by the oscilloscope will fall almost to zero. The cable screen performs the role of the Faraday cell, protecting the signal wire from the electromagnetic gaskets created by the plasma lamp.