Electric field. Types and work. Application and properties. Electrostatic field and its characteristics What fields are called electrostatic

A constant electrostatic field (ESF) is a field of stationary electric charges that interacts between them

Static current is a set of phenomena associated with the occurrence and preservation of a free electric charge on the surface and in the volume of dielectric and semiconductor substances, materials, products or on insulated conductors.

The occurrence of charges of static electricity occurs during deformation, crushing of substances, the relative movement of two bodies in contact, layers of liquid and bulk materials, with intensive mixing, crystallization, and also due to ind.

ESP is characterized by tension (B). Tension. ESP is the ratio of the force acting in the field on a point electric charge to the magnitude of this charge. A unit of measure for tension. ESP is volts per meter (V/m mm).

ESP is created in power plants and during electrical processes, depending on the source of formation, they can exist in the form of their own electrostatic field (field of stationary charges) or a stationary electric field (electric field of direct current).

Where are ESPs used?

ESPs are widely used in electrogas cleaning, electrostatic separation of materials, electrostatic application of paint and varnish and polymer materials, and in other production processes.

In the radio-electronic industry, static current is generated during transportation, grinding, polishing of radio and television receivers, in the premises of computer centers, as well as in other processes where dielectric materials are used, which are side and undesirable production factors.

ESP arising from the processing of chemical fiber has high dielectric properties. The level of tension. ESP on spinning and weaving equipment reaches 20-60 kV/m

In the chemical industry, in the production of plastic materials and products from them (tire cord, linoleum, etc.), electrostatic charges and fields with a strength of 240-250 kV / m are formed

How does ESP affect the human body?

biological action. ESP on the human body determines the greatest sensitivity to electrostatic fields of the nervous, cardiovascular, neurohumoral and other body systems

Workers working in the zone of action of the electric field, there are various complaints of irritability, headache, sleep disturbance, loss of appetite, etc.

People who are subject to. ESP is characterized by the appearance of peculiar "phobias" due to the fear of waiting for a discharge. The tendency to "phobias" is mainly accompanied by increased emotional excitability

How is hygienic regulation of electrostatic fields carried out?

The intensity of the electrostatic field is normalized by the standard. GOST 121045-84 "Electrostatic fields. Permissible levels at workplaces and?? requirements for monitoring"

This standard applies to. ESP arising from the operation of high-voltage DC electrical equipment and the electrization of dielectric materials. This standard establishes additional permissible levels of electrostatic fields in the workplace, as well as general requirements for monitoring and protective equipment.

Permissible tension levels. ESP are set depending on the time spent at the workplace

The maximum permissible level of tension. ESP (E, ra") is accepted according to the standard 60 kV / m for one hour

If the strength of electrostatic fields up to 20 kV / m, the residence time in. ESP is not regulated

In the tension range from 20 to 60 kV / m, the allowable residence time of workers in. ESP without protective equipment (/, year) is determined by the formula:

Where. E ^ - the actual value of tension. ESP, kV / m

To determine tension. ESP used electrostatic field strength meter

What are the protective means against the effects of ESP?

The use of protective equipment working is mandatory in cases where the actual tension levels. ESP at workplaces exceed 60 kV/m

For impact protection. ESPs are used: shielding sources of the workplace field, neutralizers of static shock, limiting the operating time, etc.

When choosing means of protection against static electricity, the features of technological processes, the physical and chemical properties of the processed materials, the microclimate of industrial premises, etc., should be taken into account. The above factors determine a differentiated approach to the development of protective equipment.

Reducing the generation of electrostatic charges or their removal from electrified materials is achieved by:

1) grounding of metal and electrically conductive elements of process equipment;

2) increase in surfaces and volume conductivity of dielectrics;

3) installation of static electricity neutralizers

Protective grounding is carried out independently of the use of other protection methods. Grounding is subject not only to the elements of technological equipment, but. And isolated electrically conductive sections of process equipment.

A sufficiently effective means of protection is an increase in air humidity up to 65-75%, if this is possible under the conditions of the technological process.

Personal protective equipment includes antistatic shoes, antistatic gowns, overalls, grounded hand protection wristbands, and other items that can provide electrostatic grounding to a person's body.

An electric field is a vector field that acts around particles that have an electric charge. It is part of the electromagnetic field. It is characterized by the absence of real visualization. It is invisible, and can only be seen as a result of force action, to which other charged bodies with opposite poles react.

How does an electric field work?

In fact, the field is a special state of matter. Its action is manifested in the acceleration of bodies or particles with an electric charge. Its characteristic features include:

• Action only in the presence of an electric charge.
• No boundaries.
• The presence of a certain amount of impact.
• The possibility of determining only by the result of the action.

The field is inextricably linked with the charges that are in a particular particle or body. It can be formed in two cases. The first provides for its appearance around electric charges, and the second when moving electromagnetic waves, when the electromagnetic field changes.

Electric fields act on electrically charged particles that are stationary relative to the observer. As a result, they gain power. An example of the impact of the field can be observed in everyday life. To do this, it is enough to create an electric charge. Physics textbooks offer the simplest example for this, when a dielectric is rubbed against a woolen product. It is quite possible to get a field by taking a plastic ballpoint pen and rubbing it against your hair. A charge forms on its surface, which leads to the appearance of an electric field. As a result, the pen attracts small particles. If it is presented to finely torn pieces of paper, they will be attracted to it. The same result can be achieved with a plastic comb.

A household example of the manifestation of an electric field is the formation of small light flashes when removing clothes made of synthetic materials. As a result of being on the body, dielectric fibers accumulate charges around them. When removing such a piece of clothing, the electric field is subjected to various forces of influence, which leads to the formation of light flashes. This is especially true for winter clothes, in particular sweaters and scarves.

Field properties

To characterize the electric field, 3 indicators are used:

• Potential.
• Tension.
• Voltage.

Potential

This property is one of the main ones. Potential indicates the amount of stored energy used to move charges. As they shift, energy is wasted, gradually approaching zero. A clear analogy of this principle can be an ordinary steel spring. In a calm position, it does not have any potential, but only until such time as it is compressed. From such an impact, it receives the energy of counteraction, therefore, after the cessation of influence, it will definitely unfold. When the spring is released, it instantly straightens. If there are objects in her path, she will start moving them. Returning directly to the electric field, the potential can be compared with the efforts applied to straighten back.

The electric field has potential energy, which makes it capable of performing a certain action. But moving the charge in space, it depletes its resource. In the same case, if the movement of the charge inside the field is carried out under the influence of an external force, then the field not only does not lose its potential, but also replenishes it.

Also, for a better understanding of this value, one more example can be given. Assume that a small positively charged charge is located far beyond the scope of the electric field. This makes it completely neutral and excludes mutual contact. If, as a result of the action of any external force, the charge moves towards the electric field, then, having reached its boundary, it will be drawn into a new trajectory. The energy of the field spent on the influence relative to the charge at a certain point of influence will be called the potential at this point.

The expression of the electric potential is carried out through the unit of measurement Volt.

tension

This measure is used to quantify the field. This value is calculated as the ratio of the positive charge of the action acting on the force. In simple terms, tension expresses the strength of the electric field in a certain place and time. The higher the tension, the more pronounced will be the influence of the field on the surrounding objects or living beings.

Voltage

This parameter is formed from the potential. It is used to demonstrate the quantitative ratio of the action that the field produces. That is, the potential itself shows the amount of accumulated energy, and the voltage shows the losses to ensure the movement of charges.

In an electric field, positive charges move from points of high potential to places where it is lower. As for the negative charges, they move in the opposite direction. As a result, work is carried out using the potential energy of the field. In fact, the voltage between the points qualitatively expresses the work done by the field to transfer a unit of oppositely charged charges. Thus, the terms voltage and potential difference are one and the same.

Visual manifestation of the field

The electric field has a conditional visual expression. For this, graphic lines are used. They coincide with the lines of action of force, which radiate charges around them. In addition to the line of action of forces, their direction is also important. To classify lines, it is customary to use a positive charge as the basis for determining directions. Thus, the field movement arrow goes from positive particles to negative ones.

Drawings depicting electric fields on the lines have a direction in the form of an arrow. Schematically, they always have a conditional beginning and end. Thus, they do not close on themselves. The lines of force originate at the location of the positive charge and end at the location of the negative particles.

The electric field can have different types of lines, depending not only on the polarity of the charge that contributes to their formation, but also on the presence of third-party factors. So, when opposite fields meet, they begin to act on each other attractively. Distorted lines take on the shape of curved arcs. In the same case, when 2 identical fields meet, they repel each other in opposite directions.

Scope of application

The electric field has a number of properties that have found useful applications. This phenomenon is used to create various equipment for work in several very important areas.

Use in medicine

The impact of an electric field on certain parts of the human body allows you to increase its actual temperature. This property has found its application in medicine. Specialized devices provide impact on the necessary areas of damaged or diseased tissues. As a result, their blood circulation improves and a healing effect occurs. The field acts with a high frequency, so the point influence on the temperature gives its results and is quite noticeable for the patient.

Application in chemistry

This field of science involves the use of various pure or mixed materials. In this regard, work with electric fields could not bypass this industry. Mixture components interact with the electric field in different ways. In chemistry, this property is used to separate liquids. This method has found laboratory application, but is also found in industry, although less frequently. For example, when exposed to a field, the separation of polluting components in oil is carried out.

The electric field is used for water filtration treatment. It is able to separate individual groups of pollutants. This processing method is much cheaper than using replacement cartridges.

electrical engineering

The use of an electric field has a very interesting application in electrical engineering. So, a method was developed from source to consumer. Until recently, all developments were theoretical and experimental. There is already an effective implementation of the USB plug-in smartphone technology. This method does not yet allow the transfer of energy over a long distance, but it is being improved. It is possible that in the near future the need for charging cables with power supplies will disappear completely.

When performing electrical installation and repair work, an LED is used, which operates on the basis of a circuit. In addition to a number of functions, it can respond to an electric field. Due to this, when the probe approaches the phase wire, the indicator starts to glow without actually touching the conductive core. It reacts to the field emanating from the conductor even through the insulation. The presence of an electric field allows you to find conductive wires in the wall, as well as determine the points of their break.

You can protect yourself from the influence of the electric field with the help of a metal screen, inside of which it will not be. This property is widely used in electronics to eliminate the mutual influence of electrical circuits that are located quite close to each other.

Future Applications

There are also more exotic possibilities for the electric field, which science does not yet possess. These are communications faster than the speed of light, teleportation of physical objects, movement in an instant between open locations (wormholes). However, to implement such plans, much more complex studies and experiments will be needed than experiments with two possible outcomes.

However, science is developing all the time, opening up new possibilities for using the electric field. In the future, its scope may expand significantly. It is possible that it will find application in all significant areas of our lives.

Coulomb's law determines the strength of the interaction between electric charges, but does not explain how this interaction is transmitted over a distance from one body to another.

Experiments show that this interaction is also observed when electrified bodies are in a vacuum. This means that no medium is needed for electrical interaction. According to the theory developed by M. Faraday and J. Maxwell, in the space where the electric charge is located, there is an electric field.

electrostatic field- a special type of matter, its source is the charges that are motionless relative to the considered inertial reference frame (ISR), through which their interaction is carried out.

Thus, the electrostatic field is material. It is continuous in space. Based on modern concepts, an immobile charged particle is a source of an electrostatic field, and the presence of a field is a sign of the existence of the charged particle itself. The interaction of electric charges is reduced to the following: the charge field q 1 acts on charge q 2 , and the charge field q 2 acts on the charge q 1 . These interactions are not transmitted instantly, but at a finite speed equal to the speed of light. With= 300000 km/s. The electric field created by stationary electric charges, relative to the considered IFR, is called electrostatic.

We cannot directly perceive an electrostatic field with our senses. We can judge the existence of an electrostatic field by its actions. The electrostatic field of the charge acts with some force on any other charge that is in the field of this charge.

The force with which an electrostatic field acts on an electric charge introduced into it is called electrical force.

The effect of an electrostatic field on a charge depends on the location of the charge in this field.

If there are several charged bodies located at different points in space, then at any point in this space there will be a joint action of all charges, i.e. the electrostatic field created by all these charged bodies.

Literature

Aksenovich L. A. Physics in high school: Theory. Tasks. Tests: Proc. allowance for institutions providing general. environments, education / L. A. Aksenovich, N. N. Rakina, K. S. Farino; Ed. K. S. Farino. - Mn.: Adukatsia i vykhavanne, 2004. - C. 214-215.

electrostatic field as well as the electric field is a special form of matter that surrounds bodies that have an electric charge. But unlike the latter, an electrostatic field is created only around motionless charged bodies, that is, when there are no conditions for creating an electric current.

An electrostatic field is characterized by properties that distinguish it from other types of fields generated in electrical circuits.

Its main difference lies in the fact that its lines of force never intersect and do not touch each other. If an electrostatic field is created by a positive charge, then its field lines begin with a charge and end somewhere in infinity. If we are dealing with a negative charge, then the lines of force of its electrostatic field, on the contrary, begin somewhere in infinity, and end on the charge itself. That is, they are directed from a positive charge or towards a negative one.

By the way, the larger the charge, the stronger the field it creates and the greater the density of its lines of force. True, the field lines of force are rather a graphic (imaginary) image of it, adopted in physics and electronics. In fact, none of the fields creates clear drawn lines.

The main characteristic by which the electrical and physical properties of an electrostatic field are judged is its intensity. It shows with what force the field acts on electric charges.

The action of some charged bodies on other charged bodies is carried out without their direct contact, by means of an electric field.

The electric field is material. It exists independently of us and our knowledge of it.

The electric field is created by electric charges and is detected using electric charges by the action of a certain force on them.

The electric field propagates with a finite speed of 300,000 km/s in a vacuum.

Since one of the main properties of the electric field is its action on charged particles with a certain force, then to introduce the quantitative characteristics of the field, it is necessary to place a small body with a charge q (test charge) at the point in space under study. A force will act on this body from the side of the field

If you change the value of the test charge, for example, twice, the force acting on it will also change twice.

When the value of the test charge changes n times, the force acting on the charge also changes n times.

The ratio of the force acting on a test charge placed at a given point of the field to the magnitude of this charge is a constant value and does not depend either on this force, or on the magnitude of the charge, or on whether there is any charge. This ratio is denoted by a letter and is taken as the power characteristic of the electric field. The corresponding physical quantity is called electric field strength .

The intensity shows what force acts from the electric field on a unit charge placed at a given point in the field.

To find the unit of tension, it is necessary to substitute the units of force - 1 N and charge - 1 C into the defining equation of tension. We get: [ E ] \u003d 1 N / 1 Cl \u003d 1 N / Cl.

For clarity, electric fields in the drawings are depicted using lines of force.

An electric field can do work to move a charge from one point to another. Hence, a charge placed at a given point in the field has a potential energy reserve.

The energy characteristics of the field can be introduced similarly to the introduction of the force characteristic.

When the value of the test charge changes, not only the force acting on it changes, but also the potential energy of this charge. The ratio of the energy of the test charge located at a given point of the field to the value of this charge is a constant value and does not depend on either the energy or the charge.

To obtain a unit of potential, it is necessary to substitute the units of energy - 1 J and charge - 1 C into the defining equation of the potential. We get: [φ] = 1 J / 1 C = 1 V.

This unit has its own name 1 volt.

The field potential of a point charge is directly proportional to the magnitude of the charge that creates the field and inversely proportional to the distance from the charge to a given point of the field:

Electric fields in the drawings can also be depicted using surfaces of equal potential, called equipotential surfaces .

When an electric charge moves from a point with one potential to a point with another potential, work is done.

A physical quantity equal to the ratio of work to move a charge from one point of the field to another, to the value of this charge, is called electric voltage :

The voltage shows what the work done by the electric field is when moving a charge of 1 C from one point of the field to another.

The unit of voltage, as well as potential, is 1 V.

The voltage between two field points located at a distance d from each other is related to the field strength:

In a uniform electric field, the work of moving a charge from one point of the field to another does not depend on the shape of the trajectory and is determined only by the magnitude of the charge and the potential difference of the points in the field.