Quantization of electric charge

Any experimentally observed electric charge is always a multiple of the elementary- this assumption was made by B. Franklin in 1752 and subsequently was repeatedly tested experimentally. Charge was first measured experimentally by Millikan in 1910.

The fact that electric charge occurs in nature only in the form of an integer number of elementary charges can be called quantization of electric charge. At the same time, in classical electrodynamics the question of the reasons for charge quantization is not discussed, since charge is an external parameter and not a dynamic variable. A satisfactory explanation of why the charge must be quantized has not yet been found, but a number of interesting observations have already been obtained.

• If there is a magnetic monopole in nature, then, according to quantum mechanics, its magnetic charge must be in a certain relationship with the charge any chosen elementary particle. It automatically follows from this that the mere existence of a magnetic monopole entails charge quantization. However, it has not yet been possible to detect a magnetic monopole in nature.
• In modern particle physics, models like preon are being developed, in which all known fundamental particles would turn out to be simple combinations of new, even more fundamental particles. In this case, the quantization of the charge of the observed particles does not seem surprising, since it arises “by construction.”
• It is also possible that all parameters of the observed particles will be described within the framework of a unified field theory, approaches to which are currently being developed. In such theories, the magnitude of the electrical charge of particles must be calculated from an extremely small number of fundamental parameters, possibly related to the structure of space-time at ultrashort distances. If such a theory is constructed, then what we observe as an elementary electric charge will turn out to be some discrete invariant of space-time. However, specific generally accepted results in this direction have not yet been obtained.

Fractional electric charge

See also

Notes

Wikimedia Foundation. 2010.

• Electric charge
• Charge

See what “Elementary electric charge” is in other dictionaries:

All matter is made up of elements. But why is everything around us so different? The answer has to do with tiny particles. They are called protons. Unlike electrons, which have a negative charge, these elementary particles have a positive charge. What are these particles and how do they work?

Protons are everywhere

Which elementary particle has a positive charge? Everything that can be touched, seen, and felt is made of atoms, the smallest building blocks that make up solids, liquids, and gases. They're too small to look at closely, but they make up things like your computer, the water you drink, and even the air you breathe. There are many types of atoms, including oxygen, nitrogen, and iron atoms. Each of these types is called elements.



Some of them are gases (oxygen). The nickel element has a silvery color. There are other features that distinguish these tiny particles from each other. What actually makes these elements different? The answer is simple: their atoms have different numbers of protons. This elementary particle has a positive charge and is located inside the center of the atom.



All atoms are unique

The atoms are very similar, but the different numbers of protons make them a unique type of element. For example, oxygen atoms have 8 protons, hydrogen atoms have only 1, and gold atoms have 79. You can tell a lot about an atom just by counting its protons. These elementary particles are located in the core itself. They were originally thought to be a fundamental particle, but recent research has shown that protons are made up of smaller ingredients called quarks.



What is a proton?

Which elementary particle has a positive charge? This is a proton. This is the name given to the subatomic particle found in the nucleus of every atom. In fact, the number of protons in each atom is the atomic number. Until recently, it was considered a fundamental particle. However, new technology has led to the discovery that the proton is made up of smaller particles called quarks. A quark is a fundamental particle of matter that has only recently been discovered.



Where do protons come from?

An elementary particle with a positive charge is called a proton. These elements can be formed as a result of the appearance of unstable neutrons. After about 900 seconds, the neutron that bounces off the nucleus will decay into other elementary particles of the atom: proton, electron and antineutrino.



Unlike a neutron, a free proton is stable. When free protons interact with each other, they form Our sun, like most other stars in the Universe, is primarily made of hydrogen. A proton is the smallest elementary particle that has a charge of +1. An electron has a charge of -1, but a neutron has no charge at all.



Subatomic particles: location and charge

Elements are characterized by their composition of subatomic elementary particles: protons, neutrons and electrons. The first two groups are located in the nucleus (center) of the atom and have a mass of one atomic mass. Electrons are found outside the nucleus, in regions called “shells.” They weigh almost nothing. When calculating atomic mass, attention is paid only to protons and neutrons. The mass of an atom is their sum.



By summing the atomic mass of all the atoms in a molecule, we can estimate the molecular mass, which is expressed in atomic mass units (called daltons). Each of the heavy particles (neutron, proton) weighs one atomic mass, so a helium (He) atom, which has two protons, two neutrons and two electrons, weighs about four atomic mass units (two protons plus two neutrons). In addition to location and mass, each subatomic particle has a property called "charge". It can be "positive" or "negative".

Elements with the same charge tend to reflect each other, and objects with opposite charges tend to attract each other. Which elementary particle has a positive charge? This is a proton. Neutrons have no charge at all, giving the nucleus an overall positive charge. Each electron has a negative charge, which is equal in strength to the positive charge of a proton. The electrons and protons in the nucleus are attracted to each other, and this is the force that holds the atom together, similar to the force of gravity that keeps the Moon in orbit around the Earth.



Stable subatomic particle

Which elementary particle has a positive charge? The answer is known: proton. In addition, it is equal in magnitude to a unit charge of an electron. However, its mass at rest is 1.67262 × 10 -27 kg, which is 1836 times the mass of the electron. Protons, together with electrically neutral particles called neutrons, make up all atomic nuclei except hydrogen. Each core of this chemical element has the same number of protons. The atomic number of this element determines its position in the periodic table.



Discovery of the proton

The elementary particle that has a positive charge is the proton, the discovery of which dates back to the earliest studies of atomic structure. By studying the flows of ionized gaseous atoms and molecules from which electrons have been removed, a positive particle was identified, equal in mass to a hydrogen atom. (1919) showed that nitrogen, when bombarded with alpha particles, ejects what appears to be hydrogen. By 1920, he isolated an elementary particle from hydrogen nuclei, calling it a proton.



High-energy particle physics research in the late twentieth century refined the structural understanding of the nature of the proton within a group of subatomic particles. Protons and neutrons have been shown to be made up of smaller particles and are classified as baryons - particles made up of three elementary units of matter known as quarks.



Subatomic particle: towards a grand unified theory

An atom is a small piece of matter that represents a specific element. For some time it was believed that it was the smallest piece of matter that could exist. But in late XIX century and early twentieth, scientists discovered that atoms are made up of certain subatomic particles and that no matter what the element, the same subatomic particles make up an atom. The number of different subatomic particles is the only thing that changes.



Scientists now recognize that there are many subatomic particles. But to be successful in chemistry, you really only need to deal with the three basic ones: protons, neutrons, and electrons. Matter can be electrically charged in one of two ways: positive or negative.

What is an elementary particle with a positive charge called? The answer is simple: the proton, it is the one that carries one unit of positive charge. And due to the presence of negatively charged electrons, the atom itself is neutral. Sometimes some atoms can gain or lose electrons and gain a charge. In this case, they are usually called ions.



Elementary particles of the atom: an ordered system

The atom has a systematic and ordered structure that ensures stability and is responsible for all kinds of properties of matter. The study of these began more than a hundred years ago, and by now we already know a lot about them. Scientists have found that most of the atom is empty and sparsely populated by “electrons.” They are negatively charged light particles that revolve around a central heavy part, which makes up 99.99% of the total mass of the atom. It was easier to figure out the nature of electrons, but after many ingenious studies it became known that the nucleus includes positive protons and neutral neutrons.



Every unit in the universe is made up of atoms

The key to understanding most of the properties of matter is that every unit in our universe is made of atoms. There are 92 naturally occurring types of atoms, and they form molecules, compounds, and other types of substances to create the complex world around us. Although the name "atom" was derived from Greek wordátomos, meaning "indivisible", modern physics has shown that it is not the ultimate building block of matter and is indeed "divided" into subatomic particles. They are the real fundamental entities that make up the entire world.

719. Law of conservation of electric charge

720. Bodies with electric charges different sign, …

They are attracted to each other.

721. Identical metal balls, charged with opposite charges q 1 = 4q and q 2 = -8q, were brought into contact and moved apart to the same distance. Each of the balls has a charge

q 1 = -2q and q 2 = -2q

723.A droplet having a positive charge (+2e) lost one electron when illuminated. The charge of the drop became equal

724. Identical metal balls charged with charges q 1 = 4q, q 2 = - 8q and q 3 = - 2q were brought into contact and moved apart to the same distance. Each of the balls will have a charge

q 1 = - 2q, q 2 = - 2q and q 3 = - 2q

725. Identical metal balls charged with charges q 1 = 5q and q 2 = 7q were brought into contact and moved apart to the same distance, and then the second and third ball with charge q 3 = -2q were brought into contact and moved apart to the same distance. Each of the balls will have a charge

q 1 = 6q, q 2 = 2q and q 3 = 2q

726. Identical metal balls charged with charges q 1 = - 5q and q 2 = 7q were brought into contact and moved apart to the same distance, and then the second and third ball with charge q 3 = 5q were brought into contact and moved apart to the same distance. Each of the balls will have a charge

q 1 =1q, q 2 = 3q and q 3 = 3q

727. There are four identical metal balls with charges q 1 = 5q, q 2 = 7q, q 3 = -3q and q 4 = -1q. First, the charges q 1 and q 2 (1st system of charges) were brought into contact and moved apart to the same distance, and then the charges q 4 and q 3 (2nd system of charges) were brought into contact. Then they took one charge each from system 1 and 2 and brought them into contact and moved them apart to the same distance. These two balls will have a charge

728. There are four identical metal balls with charges q 1 = -1q, q 2 = 5q, q 3 = 3q and q 4 = -7q. First, the charges q 1 and q 2 (1 system of charges) were brought into contact and moved apart to the same distance, and then the charges q 4 and q 3 (system 2 of charges) were brought into contact. Then they took one charge each from system 1 and 2 and brought them into contact and moved them apart to the same distance. These two balls will have a charge

729.An atom has a positive charge

Core.

730. Eight electrons move around the nucleus of an oxygen atom. The number of protons in the nucleus of an oxygen atom is

731.The electric charge of an electron is

-1.6 · 10 -19 Cl.

732.The electric charge of a proton is

1.6 · 10 -19 Cl.

733.The nucleus of a lithium atom contains 3 protons. If 3 electrons rotate around the nucleus, then

The atom is electrically neutral.

734. There are 19 particles in the fluorine nucleus, of which 9 are protons. The number of neutrons in the nucleus and the number of electrons in a neutral fluorine atom





Neutrons and 9 electrons.

735. If in any body the number of protons is greater than the number of electrons, then the body as a whole

Positively charged.

736. A droplet having a positive charge of +3e lost 2 electrons during irradiation. The charge of the drop became equal

8·10 -19 Cl.

737. A negative charge in an atom carries

Shell.

738.If an oxygen atom turns into a positive ion, then it

Lost an electron.

739.Has a large mass

Negative hydrogen ion.

740.As a result of friction, 5·10 10 electrons were removed from the surface of a glass rod. Electric charge on a stick

(e = -1.6 10 -19 C)

8·10 -9 Cl.

741.As a result of friction, the ebonite rod received 5·10 10 electrons. Electric charge on a stick

(e = -1.6 10 -19 C)

-8·10 -9 Cl.

742.The force of the Coulomb interaction of two point electric charges when the distance between them decreases by 2 times

Will increase 4 times.

743.The force of the Coulomb interaction of two point electric charges when the distance between them decreases by 4 times

Will increase 16 times.

744.Two point electric charges act on each other according to Coulomb’s law with a force of 1N. If the distance between them is increased by 2 times, then the force of the Coulomb interaction of these charges will become equal

745.Two point charges act on each other with a force of 1N. If the magnitude of each charge is increased by 4 times, then the strength of the Coulomb interaction will become equal to

746. The force of interaction between two point charges is 25 N. If the distance between them is reduced by 5 times, then the force of interaction of these charges will become equal

747.The force of the Coulomb interaction of two point charges when the distance between them increases by 2 times

Will decrease by 4 times.

748.The force of the Coulomb interaction of two point electric charges when the distance between them increases by 4 times





Will decrease by 16 times.

749. Formula of Coulomb's law

.

750. If 2 identical metal balls having charges +q and +q are brought into contact and moved apart to the same distance, then the modulus of the interaction force

It won't change.

751. If 2 identical metal balls having charges +q and -q, the balls are brought into contact and moved apart to the same distance, then the interaction force

Will become equal to 0.

752.Two charges interact in the air. If they are placed in water (ε = 81), without changing the distance between them, then the force of the Coulomb interaction

Will decrease by 81 times.

753.The force of interaction between two charges of 10 nC each, located in the air at a distance of 3 cm from each other, is equal to

()

754. Charges of 1 µC and 10 nC interact in air with a force of 9 mN at a distance

()

755. Two electrons located at a distance of 3·10 -8 cm from each other repel with a force ( ; e = - 1.6 10 -19 C)

2.56·10 -9 N.

756. When the distance from the charge increases by 3 times, the voltage module electric field

Will decrease by 9 times.

757.The field strength at a point is 300 N/C. If the charge is 1·10 -8 C, then the distance to the point

()

758. If the distance from a point charge creating an electric field increases 5 times, then the electric field strength

Will decrease by 25 times.

759.The field strength of a point charge at a certain point is 4 N/C. If the distance from the charge is doubled, the voltage will become equal to

760.Indicate the formula for the electric field strength in the general case.

761. Mathematical notation of the principle of superposition of electric fields



762.Indicate the formula for the intensity of a point electric charge Q

.

763. Electric field strength modulus at the point where the charge is located

1·10 -10 C is equal to 10 V/m. The force acting on the charge is equal to

1·10 -9 N.

765. If a charge of 4·10 -8 C is distributed on the surface of a metal ball with a radius of 0.2 m, then the charge density

2.5·10 -7 C/m2.

766.In a vertically directed uniform electric field there is a speck of dust with a mass of 1·10 -9 g and a charge of 3.2·10-17 C. If the gravity of a dust grain is balanced by the strength of the electric field, then the field strength is equal to

3·10 5 N/Cl.

767. At the three vertices of a square with a side of 0.4 m there are identical positive charges of 5·10 -9 C each. Find the tension at the fourth vertex

() 540 N/Cl.

768. If two charges are 5·10 -9 and 6·10 -9 C, so that they repel with a force of 12·10 -4 N, then they are at a distance

768. If the module of a point charge is reduced by 2 times and the distance to the charge is reduced by 4 times, then the electric field strength at a given point

Will increase 8 times.

Decreases.

770. The product of the electron charge and the potential has the dimension

Energy.

771.The potential at point A of the electric field is 100V, the potential at point B is 200V. The work done by the electric field forces when moving a charge of 5 mC from point A to point B is equal to

-0.5 J.

772. A particle with charge +q and mass m, located at points of an electric field with intensity E and potential, has acceleration

773.An electron moves in a uniform electric field along a line of tension from a point with a high potential to a point with a lower potential. Its speed is

Increasing.

774.An atom that has one proton in its nucleus loses one electron. This creates

Hydrogen ion.

775. An electric field in a vacuum is created by four point positive charges placed at the vertices of a square with side a. The potential at the center of the square is

776. If the distance from a point charge decreases by 3 times, then the field potential

Will increase 3 times.

777. When a point electric charge q moves between points with a potential difference of 12 V, 3 J of work is done. In this case, the charge is moved

778. Charge q moved from point electrostatic field to a point with potential. By which of the following formulas:

1) 2) ; 3) you can find work moving charge.

779. In a uniform electric field of strength 2 N/C, a charge of 3 C moves along the field lines at a distance of 0.5 m. The work done by the electric field forces to move the charge is equal to

780.The electric field is created by four point unlike charges placed at the vertices of a square with side a. Like charges are located at opposite vertices. The potential at the center of the square is

781. Potential difference between points lying on the same power line at a distance of 6 cm from each other, is equal to 60 V. If the field is uniform, then its strength is

782.Unit of potential difference

1 V = 1 J/1 C.

783. Let the charge move in a uniform field with intensity E = 2 V/m along a field line of 0.2 m. Find the difference between these potentials.

U = 0.4 V.

784.According to Planck's hypothesis, a completely black body emits energy

In portions.

785. Photon energy is determined by the formula

1. E =pс 2. E=hv/c 3. E=h 4. E=mc2. 5. E=hv. 6.E=hc/

1, 4, 5, 6.

786. If the energy of a quantum has doubled, then the frequency of the radiation

increased by 2 times.

787.If photons with an energy of 6 eV fall on the surface of a tungsten plate, then the maximum kinetic energy of the electrons knocked out by them is 1.5 eV. The minimum photon energy at which the photoelectric effect is possible is for tungsten equal to:

788.The following statement is correct:

1. The speed of a photon is greater than the speed of light.

2. The speed of a photon in any substance is less than the speed of light.

3. The speed of a photon is always equal to the speed of light.

4. The speed of a photon is greater than or equal to the speed of light.

5. The speed of a photon in any substance is less than or equal to the speed of light.

789.Radiation photons have a large impulse

Blue.

790. When the temperature of a heated body decreases, the maximum radiation intensity

Contents of the article

ELECTRON, an elementary particle with a negative electric charge that is part of all atoms, and therefore of any ordinary substance. It is the lightest of the electrically charged particles. Electrons are involved in almost all electrical phenomena. In a metal, some electrons are not bound to atoms and can move freely, making metals good conductors of electricity. In plasma, i.e. ionized gas, positively charged atoms also move freely, but, having a much larger mass, they move much slower than electrons, and therefore make a smaller contribution to electric current. Due to its low mass, the electron turned out to be the particle most involved in the development of quantum mechanics, the partial theory of relativity and their unification - relativistic quantum field theory. It is believed that the equations that describe the behavior of electrons under all realistically feasible physical conditions are now fully known. (True, the solution of these equations for systems containing large number electrons such as solid and condensed matter, still poses difficulties.)

All electrons are identical and obey Fermi–Dirac statistics. This circumstance is expressed in the Pauli principle, according to which two electrons cannot be in the same quantum state. One of the consequences of the Pauli principle is that the states of the most weakly bound electrons - valence electrons, which determine chemical properties atoms - depend on the atomic number (charge number), which equal to the number electrons in an atom. The atomic number is also equal to the charge of the nucleus, expressed in units of proton charge e. Another consequence is that the electron “clouds” that envelop the nuclei of atoms resist their overlap, as a result of which ordinary matter tends to occupy a certain space. As befits an elementary particle, the number of main characteristics of an electron is small, namely mass ( m e» 0.51 MeV » 0.91H 10 –27 g), charge (- e" - 1.6H 10 –19 Kl) and spin (1 / 2 ћ » 1/ 2 H 0.66 H 10 –33 JH s, where is Planck’s constant h, divided by 2 p). All other characteristics of the electron are expressed through them, for example the magnetic moment (» 1.001 m 3 » 1.001H 0.93H 10 –23 J/T), with the exception of two more constants characterizing the weak interaction of electrons ( cm. below).

The first indications that electricity is not a continuous flow, but is transferred in discrete portions, were obtained in experiments on electrolysis. The result was one of Faraday's laws (1833): the charge of each ion is equal to an integer multiple of the charge of the electron, now called the elementary charge e. The name "electron" originally referred to this elementary charge. The electron in the modern sense of the word was discovered by J. Thomson in 1897. Then it was already known that during an electrical discharge in a rarefied gas, “cathode rays” appear, carrying a negative electric charge and going from the cathode (negatively charged electrode) to the anode (positively charged electrode). Studying the influence of electric and magnetic fields on a beam of cathode rays, Thomson came to the conclusion: if we assume that the beam consists of particles whose charge does not exceed elementary charge ions e, then the mass of such particles will be thousands of times less than the mass of an atom. (Indeed, the mass of an electron is approximately 1/1837 of the mass of the lightest atom, hydrogen.) Shortly before this, H. Lorentz and P. Zeeman had already obtained evidence that electrons are part of atoms: studies of the effect of a magnetic field on atomic spectra (Zeemann effect) showed that the charged particles in the atom, due to the presence of which light interacts with the atom, have the same charge-to-mass ratio as that established by Thomson for cathode ray particles.

The first attempt to describe the behavior of an electron in an atom was associated with Bohr's model of the atom (1913). The idea of ​​the wave nature of the electron, put forward by L. de Broglie (1924) (and confirmed experimentally by K. Davisson and L. Germer in 1927), served as the basis wave mechanics, developed by E. Schrödinger in 1926. At the same time, based on the analysis of atomic spectra, S. Goudsmit and J. Uhlenbeck (1925) concluded that the electron has a spin. A strict wave equation for the electron was obtained by P. Dirac (1928). The Dirac equation is consistent with the partial theory of relativity and adequately describes the spin and magnetic moment of the electron (without taking into account radiative corrections).

The Dirac equation implied the existence of another particle - a positive electron, or positron, with the same mass and spin values ​​as the electron, but with the opposite sign of the electric charge and magnetic moment. Formally, the Dirac equation allows for the existence of an electron with a total energy of either i mс 2 (mс 2 – electron rest energy), or Ј – mс 2 ; the absence of radiative transitions of electrons to states with negative energies could be explained by assuming that these states are already occupied by electrons, so that, according to the Pauli principle, there is no room for additional electrons. If one electron is removed from this Dirac “sea” of electrons with negative energies, the resulting electron “hole” will behave like a positively charged electron. The positron was discovered in cosmic rays by K. Anderson (1932).

According to modern terminology, an electron and a positron are antiparticles in relation to each other. According to relativistic quantum mechanics, for particles of any kind there are corresponding antiparticles (the antiparticle of an electrically neutral particle can coincide with it). An individual positron is as stable as an electron, whose lifetime is infinite, since there are no lighter particles with the charge of an electron. However, in ordinary matter, a positron sooner or later combines with an electron. (Initially, an electron and a positron may briefly form an “atom” called positronium, similar to a hydrogen atom in which the positron plays the role of a proton.) This joining process is called electron-positron annihilation; in it, the total energy, momentum and angular momentum are conserved, and the electron and positron are converted into gamma quanta, or photons - usually there are two of them. (From the point of view of the “sea” of electrons, this process is a radiative transition of an electron into a so-called hole - an unoccupied state with negative energy.) If the velocities of the electron and positron are not very high, then the energy of each of the two gamma quanta is approximately equal mс 2. This characteristic annihilation radiation allows positrons to be detected. For example, such radiation was observed emanating from the center of our Galaxy. The reverse process of converting electromagnetic energy into an electron and a positron is called the birth of an electron-positron pair. Typically, a high-energy gamma ray is “converted” into such a pair when flying close to atomic nucleus(the electric field of the nucleus is necessary, since the transformation of a single photon into an electron-positron pair would violate the laws of conservation of energy and momentum). Another example is the decay of the first excited state of the 16 O nucleus, an isotope of oxygen.

The emission of electrons is accompanied by one of the types of radioactivity of nuclei. This is beta decay - a process caused by weak interaction, in which a neutron in the original nucleus turns into a proton. The name of the decay comes from the name “beta rays,” historically assigned to one of the types of radioactive radiation, which, as it turned out, are fast electrons. The energy of the electrons of this radiation does not have a fixed value, since (in accordance with the hypothesis put forward by E. Fermi) during beta decay, another particle is emitted - a neutrino, which carries away part of the energy released during nuclear transformation. The basic process is:

Neutron ® proton + electron + antineutrino.

The emitted electron is not contained in the neutron; the appearance of an electron and an antineutrino represents the “birth of a pair” from energy and electric charge released during nuclear transformation. There is also beta decay with the emission of positrons, in which a proton in the nucleus is converted into a neutron. Similar transformations can also occur as a result of electron absorption; the corresponding process is called TO-capture. Electrons and positrons are emitted during beta decay of other particles, such as muons.

Role in science and technology.

Fast electrons are widely used in modern science and technology. They are used to obtain electromagnetic radiation, for example, X-rays, which arise as a result of the interaction of fast electrons with matter, and for the generation of synchrotron radiation, which occurs when they move in a strong magnetic field. Accelerated electrons are used directly, for example, in an electron microscope, or at higher energies to probe nuclei. (In such studies, the quark structure of nuclear particles was discovered.) Electrons and positrons of ultra-high energies are used in electron-positron storage rings - installations similar to particle accelerators. Due to their annihilation, storage rings make it possible to obtain elementary particles with a very large mass with high efficiency.

LECTURE 1.ELECTRIC FIELD, ITS CHARACTERISTICS. GAUSS'S THEOREM

We begin our consideration of this topic with the concept of the basic forms of matter: substance and field.

All substances, both simple and complex, are made up of molecules, and molecules are made up of atoms.

Molecule- the smallest particle of a substance that retains its chemical properties.

Atom- the smallest particle of a chemical element that retains its properties. An atom consists of a positively charged nucleus, which includes protons and neutrons (nucleons), and negatively charged electrons located on shells around the nucleus at various distances from it. If they say that an atom is electrically neutral, this means that the number of electrons on the shells is equal to the number of protons in the nucleus, because a neutron has no charge.

Electric charge– a physical quantity that determines the intensity of electromagnetic interaction. The particle charge is denoted q and is measured in Kl (Coulomb) in honor of the French scientist Charles Coulomb. An electron has an elementary (indivisible) charge; its charge is equal to q e = -1.610 -19 C. The charge of a proton is equal in absolute value to the charge of an electron, i.e. q p = 1.610 -19 C, therefore, there are positive and negative electric charges. Moreover, like charges repel, and unlike charges attract.

If a body is charged, this means that it is dominated by charges of one sign (“+” or “-”); in an electrically neutral body, the number of “+” and “-” charges is equal.

A charge is always associated with some particle. There are particles that do not have an electric charge (neutron), but there is no charge without a particle.

The concept of electric field is inextricably linked with the concept of electric charge. There are several types of fields:

electrostatic field is the electric field of stationary charged particles;

an electric field is matter that surrounds charged particles, is inextricably linked with them and exerts a force on an electrically charged body brought into a space filled with this type of matter;

magnetic field is matter that surrounds any moving charged body;

An electromagnetic field is characterized by two interconnected sides - components: a magnetic field and an electric one, which are identified by the force exerted on charged particles or bodies.

How to determine whether an electric field exists at a given point in space or not? We cannot touch the field, see it, or smell it. To determine the existence of a field, it is necessary to introduce a test (point) electric charge q 0 into any point in space.

The charge is called point, if its linear dimensions are very small compared to the distance to those points at which its field is determined.

Let the field be created by a positive charge q. To determine the magnitude of the field of this charge, it is necessary to introduce a test charge q 0 into any point in the space surrounding this charge. Then, from the electric field of the charge +q, a certain force will act on the charge q 0.

This force can be determined using Coulomb's law: the magnitude of the force with which each of two point bodies is affected by their common electric field is proportional to the product of the charges of these bodies, inversely proportional to the square of the distance between them and depends on the environment in which these bodies are located:

F = q 1  q 2 /4  0 r 2 ,

where 1/4 0 = k = 910 9 Nm 2 /Cl 2;

q 1, q 2 – particle charges;

r – distance between particles;

 0 – absolute dielectric constant of vacuum (electric constant, equal to:  0 = 8.8510 -12 F/m);

 is the absolute dielectric constant of the medium, showing how many times the electric field in the medium is less than in vacuum.