Positive and negative charges. Electric charge and elementary particles

Themes of the USE codifier: electrification of bodies, interaction of charges, two types of charge, the law of conservation of electric charge.

Electromagnetic interactions are among the most fundamental interactions in nature. The forces of elasticity and friction, gas pressure and much more can be reduced to electromagnetic forces between particles of a substance. Electromagnetic interactions themselves are no longer reduced to other, deeper types of interactions.

An equally fundamental type of interaction is gravitation - the gravitational attraction of any two bodies. However, there are several important differences between electromagnetic and gravitational interactions.

1. Not everyone can participate in electromagnetic interactions, but only charged bodies (having electric charge).

2. Gravitational interaction is always the attraction of one body to another. Electromagnetic interactions can be both attraction and repulsion.

3. Electromagnetic interaction is much more intense than gravitational one. For example, the force of electrical repulsion of two electrons is times greater than the force of their gravitational attraction to each other.

Each charged body has a certain amount of electric charge. Electric charge is a physical quantity that determines the strength of the electromagnetic interaction between objects of nature... The unit of measure for charge is pendant (Cl).

Two types of charge

Since gravitational interaction is always attraction, the masses of all bodies are non-negative. But this is not the case for charges. It is convenient to describe two types of electromagnetic interaction - attraction and repulsion - by introducing two types of electric charges: positive and negative.

Charges of different signs are attracted to each other, and charges of different signs are repelled from each other. This is illustrated in Fig. one ; the balls suspended on threads are given charges of one sign or another.

Figure: 1. Interaction of two types of charges

The ubiquitous manifestation of electromagnetic forces is explained by the fact that charged particles are present in the atoms of any substance: positively charged protons enter the nucleus of an atom, and negatively charged electrons move in orbits around the nucleus.

The charges of a proton and an electron are equal in magnitude, and the number of protons in the nucleus is equal to the number of electrons in orbits, and therefore it turns out that the atom as a whole is electrically neutral. That is why, under normal conditions, we do not notice the electromagnetic effect from the surrounding bodies: the total charge of each of them is equal to zero, and the charged particles are evenly distributed over the volume of the body. But when electroneutrality is violated (for example, as a result electrification) the body immediately begins to act on the surrounding charged particles.

Why there are exactly two types of electric charges, and not some other number of them, is not known at the moment. We can only assert that the acceptance of this fact as the primary one gives an adequate description of electromagnetic interactions.

The proton charge is equal to C. The charge of an electron is opposite in sign and is equal to C. The quantity

called elementary charge... This is the minimum possible charge: free particles with a lower charge were not found in experiments. Physics cannot yet explain why nature has the smallest charge and why its magnitude is exactly that.

The charge of any body always consists of whole number of elementary charges:

If, then the body has an excess of electrons (compared to the number of protons). If, on the contrary, the body lacks electrons: there are more protons.

Electrifying bodies

For a macroscopic body to exert an electrical effect on other bodies, it must be electrified. Electrification is a violation of the electrical neutrality of the body or its parts. As a result of electrification, the body becomes capable of electromagnetic interactions.

One of the ways to electrify a body is to impart an electric charge to it, that is, to achieve an excess of charges of the same sign in a given body. This is not difficult to do with friction.

So, when a glass rod is rubbed with silk, part of its negative charges goes to silk. As a result, the wand is charged positively and the silk negatively. But when rubbing an ebony stick with wool, some of the negative charges pass from the wool to the stick: the stick is charged negatively, and the wool is positively charged.

This method of electrifying bodies is called electrification by friction... You encounter electrifying friction whenever you take off your sweater over your head ;-)

Another type of electrification is called electrostatic induction, or electrification through influence... In this case, the total charge of the body remains equal to zero, but is redistributed in such a way that positive charges accumulate in some parts of the body, and negative charges in others.

Figure: 2. Electrostatic induction

Let's take a look at fig. 2. At some distance from the metal body there is a positive charge. It attracts negative charges of the metal (free electrons), which accumulate on the areas of the body surface closest to the charge. In the distant areas, uncompensated positive charges remain.

Despite the fact that the total charge of the metal body remained equal to zero, spatial separation of charges took place in the body. If we now divide the body along the dotted line, then the right half will be negatively charged, and the left - positively.

You can observe the electrification of the body using an electroscope. A simple electroscope is shown in Fig. 3 (image from en.wikipedia.org).

Figure: 3. Electroscope

What happens in this case? A positively charged stick (for example, previously rubbed) is brought to the disk of the electroscope and collects a negative charge on it. Below, on the moving leaves of the electroscope, there are uncompensated positive charges; pushing off from each other, the leaves diverge in different directions. If you remove the wand, the charges will return to their place and the leaves will fall back.

The phenomenon of electrostatic induction is observed on a grand scale during a thunderstorm. In fig. 4 we see a thundercloud going over the ground.

Figure: 4. Electrification of the earth by a thundercloud

Inside the cloud, there are pieces of ice of different sizes, which are mixed by ascending air currents, collide with each other and become electrified. In this case, it turns out that a negative charge accumulates in the lower part of the cloud, and a positive charge in the upper part.

The negatively charged lower part of the cloud induces charges of a positive sign below it on the surface of the earth. A giant capacitor appears with a colossal voltage between the cloud and the ground. If this voltage is sufficient for the breakdown of the air gap, then a discharge will occur - the lightning well known to you.

Charge conservation law

Let's go back to the example of electrification by friction - rubbing a stick with a cloth. In this case, the stick and the piece of cloth acquire charges of equal magnitude and opposite in sign. Their total charge was equal to zero before the interaction, and remains equal to zero after the interaction.

We see here charge conservation lawwhich reads: in a closed system of bodies, the algebraic sum of charges remains unchanged for any processes occurring with these bodies:

The closedness of a system of bodies means that these bodies can exchange charges only among themselves, but not with any other objects external to this system.

When the stick is electrified, there is nothing surprising in the conservation of charge: how many charged particles left the stick - the same amount came to a piece of cloth (or vice versa). It is surprising that in more complex processes accompanied by mutual transformations elementary particles and change in number charged particles in the system, the total charge is still conserved!

For example, in Fig. 5 shows a process in which a portion of electromagnetic radiation (the so-called photon) turns into two charged particles - an electron and a positron. Such a process turns out to be possible under certain conditions - for example, in the electric field of an atomic nucleus.

Figure: 5. Creation of an electron-positron pair

The charge of a positron is equal in magnitude to the charge of an electron and opposite in sign. The charge conservation law is fulfilled! Indeed, at the beginning of the process we had a photon whose charge is equal to zero, and at the end we got two particles with zero total charge.

The law of conservation of charge (along with the existence of the smallest elementary charge) is today the primary scientific fact. Physicists have not yet succeeded in explaining why nature behaves this way and not otherwise. We can only state that these facts are confirmed by numerous physical experiments.

I think I was not the only one who wanted and wants to combine the formula describing the gravitational interaction of bodies (The law of universal gravitation) , with the formula for the interaction of electric charges (Coulomb's law ). So let's do it!

It is necessary to put an equal sign between the concepts weight and positive charge as well as between the concepts anti-mass and negative charge .

Positive charge (or mass) characterizes Yin particles (with Fields of Attraction) - i.e. absorbing ether from the surrounding etheric field.

A negative charge (or anti-mass) characterizes the Yang particles (with Repulsive Fields) - i.e. emitting ether into the surrounding etheric field.

Strictly speaking, mass (or positive charge), as well as anti-mass (or negative charge) indicate to us that a given particle absorbs (or emits) Ether.

As for the position of electrodynamics that there is a repulsion of charges of the same sign (both negative and positive) and the attraction to each other of charges of different signs, it is not entirely accurate. And the reason for this is not entirely correct interpretation of experiments on electromagnetism.

Particles with Fields of Attraction (positively charged) will never repel each other. They only attract. But particles with Repulsive Fields (negatively charged), in fact, will always repel each other (including from the negative pole of the magnet).

Particles with Fields of Attraction (positively charged) attract any particles to themselves: both negatively charged (with Repulsive Fields) and positively charged (with Fields of Attraction). However, if both particles have a Field of Attraction, then the one, whose Field of Attraction is greater, will to a greater extent displace another particle towards itself than a particle with a smaller Field of Attraction will do.

Substance is antimatter.

In physics matter they call bodies, as well as the chemical elements of which these bodies are built, and also elementary particles. In general, it can be considered approximately correct to use the term in this way. After all Matter , from an esoteric point of view, these are power centers, spheres of elementary particles. Chemical elements are built from elementary particles, and bodies from chemical elements. But in the end it turns out that everything consists of elementary particles. But to be precise, around us we see not Matter, but Souls - i.e. elementary particles. An elementary particle, in contrast to the power center (i.e., the Soul, in contrast to Matter), is endowed with quality - Ether is created in it and disappears.

Concept substance can be considered a synonym for the concept of matter used by physics. Substance is, in the literal sense, what the things surrounding a person are made of, i.e. chemical elements and their compounds. And chemical elements, as already mentioned, consist of elementary particles.

For matter and matter in science, there are antonymic concepts - antimatter and antimatter , which are synonymous with each other.

Scientists acknowledge the existence of antimatter. However, what they take for antimatter is not, in reality. In fact, antimatter has always been at hand with science and has been indirectly discovered a long time ago, since experiments on electromagnetism began. And we can constantly feel the manifestations of its existence in the world around us. Antimatter appeared in the Universe together with matter at the very moment when elementary particles (Souls) appeared. Substance - these are Yin particles (i.e. particles with Fields of Attraction). Antimatter (antimatter) are Yang particles (particles with Repulsive Fields).

The properties of the Yin and Yang particles are directly opposite, and therefore they are perfectly suitable for the role of the sought substance and antimatter.

Ether filling elementary particles - their driving factor

"The force center of an elementary particle always tends to move together with the Ether, which at the moment fills this particle (and forms it), in the same direction and with the same speed."

Ether is the driving factor of elementary particles. If the Ether, which fills the particle, is at rest, then the particle itself will be at rest. And if the Ether of the particle moves, the particle will also move.

Thus, due to the fact that there is no difference between the Ether of the etheric field of the Universe and the Ether of particles, all the Principles of Ether's behavior are applicable to elementary particles. If the Ether, which belongs to the particle, at the moment is moving towards the appearance of the lack of Ether (in accordance with the first principle of Ether's behavior - "There are no etheric voids in the etheric field") or moves away from the excess (in accordance with the second principle of Ether's behavior - In the ether field does not create areas with excess ether density ”), the particle will move with it in the same direction and with the same speed.

What is Strength? Force Classification

One of the fundamental quantities in physics in general, and especially in one of its subsections - in mechanics, is Force ... But what is it, how to characterize it and support it with something that exists in reality?

First, let's open any Physical Encyclopedic Dictionary and read the definition.

« Force in mechanics, a measure of the mechanical action of other bodies on a given material body ”(FES,“ Power ”, ed. by AM Prokhorov).

As you can see, the Force in modern physics does not carry information about something concrete, material. But at the same time, the manifestations of the Force are more than specific. In order to remedy the situation, we need to look at the Force from the perspective of the occult.

From an esoteric point of view Force - it is nothing but Spirit, Ether, Energy. And the Soul, as you remember, is also a Spirit, only "twisted in a ring." Thus, the free Spirit is both Power, and the Soul (locked Spirit) is Power. This information will help us a lot in the future.

Despite some vagueness of the definition of Force, it has a completely material basis. This is not at all an abstract concept as it appears in physics at the present time.

Force - this is the reason forcing Ether to approach its deficiency or move away from its excess. We are interested in the Ether, enclosed in Elementary particles (Souls), therefore, for us, the Force is, first of all, the reason that prompts the particles to move. Any elementary particle is a Force, since it directly or indirectly affects other particles.

Force can be measured using speed, with which the Ether of the particle would move under the influence of this Force, do not act on the particle any other Forces. Those. the speed of the etheric flow that makes the particle move, this is the magnitude of this Force.

Let's classify all types of Forces arising in particles, depending on the cause that causes them.

The Force of Attraction (Aspiration of Attraction).

Any defect of Ether that arises anywhere in the etheric field of the Universe is the cause of the appearance of this Force.

Those. the cause of the appearance of the Force of Attraction in a particle is any other particle that absorbs Ether, i.e. forming the Field of Attraction.

Repulsion Force (Repulsion Aspiration).

The cause of the emergence of this Force is any excess of Ether that arises anywhere in the etheric field of the Universe.

Electric charge is a physical quantity that is inherent in some elementary particles. It manifests itself through the forces of attraction and repulsion between charged bodies through an electromagnetic field. Consider the physical properties of the charge and the types of charges.

General understanding of electric charge

Matter, which has a nonzero electric charge, actively interacts with the electromagnetic field and, in turn, creates this field. The interaction of a charged body with an electromagnetic field is one of four types of force interactions that are known to man. Speaking about charges and types of charges, it should be noted that from the point of view of the standard model, an electric charge reflects the ability of a body or particle to exchange carriers of an electromagnetic field - photons - with another charged body or an electromagnetic field.

One of the important characteristics of various types of charge is the preservation of their sum in an isolated system. That is, the total charge remains for an arbitrarily long time, regardless of the type of interaction that takes place inside the system.

The electrical charge is not continuous. In the experiments of Robert Millikan, the discrete nature of the electric charge was demonstrated. The types of charges that exist in nature can be positive or negative.

Positive and negative charges

Protons and electrons are carriers of two types of charges. For historical reasons, the charge of an electron is considered negative, has a value of -1 and is denoted by -e. The proton has a positive charge of +1 and is denoted + e.

If the body contains more protons than electrons, then it is considered positively charged. A striking example of a positive charge in nature is the charge of a glass rod after rubbing with a silk cloth. Accordingly, if the body contains more electrons than protons, it is assumed to be negatively charged. This kind of electrical charge is observed on a plastic ruler when rubbed with wool.

Note that the charge of a proton and an electron, although very small, is not elementary. Found quarks - "bricks" that form elementary particles, which have charges ± 1/3 and ± 2/3 relative to the charge of the electron and proton.

unit of measurement

The types of charges, both positive and negative, in the international SI system of units are measured in coulombs. A 1 coulomb charge is a very large charge, which is defined as passing through the cross section of a conductor in 1 second at a current of 1 ampere in it. One coulomb corresponds to 6.242 * 10 18 free electrons. This means that the charge of one electron is -1 / (6.242 * 10 18) \u003d - 1.602 * 10 -19 coulomb. The same value, only with a plus sign, is characteristic of another type of charge in nature - the positive charge of a proton.

A brief history of electrical charge

It has been known since the days of ancient Greece that if you rub your skin against amber, it acquires the ability to attract light bodies, for example, straw or bird feathers. This discovery belongs to the Greek philosopher Thales of Miletus, who lived 2500 years ago.

In 1600, English physician William Gilbert noticed that many materials behave like amber when rubbed. The word "amber" in ancient Greek sounds like "electron". Gilbert began to use this term for all such phenomena. Later, other terms such as "electricity" and "electric charge" appeared. In his works, Gilbert was also able to distinguish between magnetic and electrical phenomena.

The discovery of the existence of attraction and repulsion between electrically charged bodies belongs to physicist Stephen Gray. The first scientist to suggest the existence of two types of electric charges was the French chemist and physicist Charles François Dufay. The phenomenon of electric charge was also studied in detail by Benjamin Franklin. At the end of the 18th century, the French physicist Charles Augustin de Coulomb discovered his famous law.

Nevertheless, all these observations were able to form into a coherent theory of electricity only by the middle of the 19th century. It should be noted here the importance of the work of Michael Faraday on the study of electrolysis processes and James Maxwell, who fully described electromagnetic phenomena.

Modern ideas about the nature of electricity and discrete electric charge owe their existence to the work of Joseph Thomson, who discovered the electron, and Robert Millikan, who measured its charge.

Magnetic moment and electric charge

Charge types were also identified by Benjamin Franklin. There are two of them: positive and negative. Two charges of the same sign repel, and the opposite one attracts.

With the advent of quantum mechanics and the physics of elementary particles, it was shown that in addition to the electric charge, particles have a magnetic moment, which is called spin. Due to the electrical and magnetic properties of elementary particles, an electromagnetic field exists in nature.

The principle of conservation of electrical charge

According to the results of many experiments, the principle of conservation of electric charge states that there is no way to destroy a charge, or create it from nothing, and that in any electromagnetic process in an isolated system, the total electric charge is conserved.

As a result of the electrification process, the total number of protons and electrons does not change, there is only a separation of charges. An electric charge can appear in any part of the system, where it was not previously, but the total charge of the system will still not change.

Electric charge density

The charge density is understood as its amount per unit length, area or volume of space. In this regard, one speaks of three types of its density: linear, surface and volumetric. Since there are two kinds of charge, the density can also be positive and negative.

Despite the fact that the electric charge is quantized, that is, it is discrete, in a number of experiments and processes the number of its carriers is so large that it can be considered that they are evenly distributed throughout the body. This good approximation provides a number of important experimental laws for electrical phenomena.

Exploring the behavior of two point charges on a torsion balance, that is, those for which the distance between them significantly exceeds their size, Charles Coulomb in 1785 discovered the law of interaction between electric charges. The scientist formulated this law as follows:

The magnitude of each force with which two point charges interact at rest is directly proportional to the product of their electric charges and inversely proportional to the square of the distance separating them. The forces of interaction are directed along the line that connects the charged bodies.

Note that Coulomb's law does not depend on the type of charges: a change in the sign of the charge will only change the direction of the acting force to the opposite, while maintaining its modulus. The coefficient of proportionality in Coulomb's law depends on the dielectric constant of the medium in which the charges are considered.

Thus, the formula for the Coulomb force is written in the following form: F \u003d k * q 1 * q 2 / r 2, where q 1, q 2 are the magnitudes of the charges, r is the distance between the charges, k \u003d 9 * 10 9 N * m 2 / Cl 2 - proportionality coefficient for vacuum.

The constant k through the universal dielectric constant ε 0 and the dielectric constant of the material ε is expressed as follows: k \u003d 1 / (4 * pi * ε * ε 0), here pi is the number pi, and ε\u003e 1 for any medium.

Coulomb's law is not valid in the following cases:

• when charged particles begin to move, and especially when their speeds approach near light speeds;
• when the distance between the charges is small compared to their geometric dimensions.

It is interesting to note that the mathematical form of Coulomb's law coincides with that for the law of universal gravitation, in which the role of the electric charge is played by the mass of the body.

Methods of transferring electric charge and electrification

Electrification is understood as the process as a result of which an electrically neutral body acquires a charge other than zero. This process is associated with the movement of elementary charge carriers, most often electrons. You can electrify your body in the following ways:

• As a result of contact. If a charged body touches another body consisting of a conductive material, the latter will acquire an electric charge.
• Friction of insulator against other material.
• Electrical induction. The essence of this phenomenon lies in the redistribution of electric charges inside the body due to the influence of an external electric field.
• The phenomenon of the photoelectric effect, in which electrons are ejected from a solid due to exposure to electromagnetic radiation.
• Electrolysis. A physicochemical process that takes place in melts and solutions of salts, acids and alkalis.
• Thermoelectric effect. In this case, electrification occurs due to temperature gradients in the body.

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Typically, an atom has the same number of protons and electrons. When this is the case, the atom is electrically neutral because the positively charged protons are precisely balanced by the negatively charged electrons. However, in some cases, the atom loses its electrical equilibrium due to the loss or capture of an electron. When an electron is lost or captured, the atom is no longer neutral. It is either positively or negatively charged, depending on the loss or capture of an electron. Thus, a charge exists in an atom when the number of its protons and electrons does not coincide.

Under certain conditions, some atoms can lose a small number of electrons for a short period of time. The electrons of the atoms of some substances, especially metals, can easily be knocked out of their outer orbits. Such electrons are called free electrons, and the materials containing them are called conductors. When electrons leave an atom, the latter takes on a positive charge as the negatively charged electron is removed, upsetting the electrical balance in the atom.

The atom can just as easily capture additional electrons. In this case, it acquires a negative charge.

The charge is thus created when there is an excess of electrons or protons in the atom. When one atom is charged and the other contains a charge of the opposite sign, electrons can flow from one atom to another. This electron flow is called electric current.

An atom that has lost or captured an electron is considered unstable. An excess of electrons creates a negative charge in it. Lack of electrons is a positive charge. Electric charges interact with each other in various ways. Two negatively charged particles repel each other, while positively charged particles repel each other. Two charges of opposite signs are mutually attracted. The law of electric charges says: charges with the same signs are repelled, and those with opposite signs are attracted. 1.2 serves as an illustration to the law of electric charges.

All atoms tend to remain neutral as the electrons in the outer orbits repel the rest of the electrons. However, many materials can acquire a positive or negative charge due to mechanical influences, such as friction. The well-known crackling sound of an ebony comb moving through hair on a dry winter day is an example of the generation of electrical charge through friction.

Definition 1

Many of the physical phenomena around us that occur in nature do not find an explanation in the laws of mechanics, thermodynamics and molecular kinetic theory. Such phenomena are based on the influence of forces acting between bodies at a distance and independent of the masses of interacting bodies, which immediately denies their possible gravitational nature. These forces are called electromagnetic.

Even the ancient Greeks had some idea of \u200b\u200belectromagnetic forces. However, it was only at the end of the 18th century that a systematic, quantitative study of physical phenomena associated with the electromagnetic interaction of bodies began.

Definition 2

Thanks to the painstaking work of a large number of scientists in the 19th century, the creation of an absolutely new harmonious science was completed, dealing with the study of magnetic and electrical phenomena. So one of the most important branches of physics was named electrodynamics.

The electric and magnetic fields created by electric charges and currents became its main objects of study.

The concept of charge in electrodynamics plays the same role as gravitational mass in Newtonian mechanics. It is included in the foundation of the section and is primary for it.

Definition 3

Electric charge is a physical quantity that characterizes the property of particles or bodies to enter into electromagnetic force interactions.

The letters q or Q in electrodynamics usually denote an electric charge.

Together, all the known experimentally proven facts enable us to draw the following conclusions:

Definition 4

There are two kinds of electric charges. These are conventionally named positive and negative charges.

Definition 5

Charges can transfer (for example, by direct contact) between bodies. Electric charge, in contrast to body weight, is not an integral characteristic of it. One specific body in different conditions can take on a different charge value.

Definition 6

Like charges repel, unlike charges attract. This fact reveals another fundamental difference between electromagnetic and gravitational forces. Gravitational forces are always gravitational forces.

The law of conservation of electric charge is one of the fundamental laws of nature.

In an isolated system, the algebraic sum of the charges of all bodies is unchanged:

q 1 + q 2 + q 3 +. ... ... + q n \u003d c o n s t.

Definition 7

The law of conservation of electric charge states that in a closed system of bodies, the processes of creation or disappearance of charges of only one sign cannot be observed.

From the point of view of modern science, elementary particles are charge carriers. Any ordinary object is made of atoms. They include protons carrying a positive charge, negatively charged electrons and neutral particles - neutrons. Protons and neutrons are an integral part of atomic nuclei, while electrons form the electron shell of atoms. In modulus, the electric charges of a proton and an electron are equivalent and equal to the value of the elementary charge e.

In a neutral atom, the number of electrons in the shell and protons in the nucleus is the same. The number of any of the listed particles is called the atomic number.

Such an atom has the ability to both lose and gain one or more electrons. When this happens, the neutral atom becomes a positively or negatively charged ion.

The charge can pass from one body to another only in portions, which contain an integer number of elementary charges. It turns out that the electric charge of the body is a discrete quantity:

q \u003d ± n e (n \u003d 0, 1, 2,...).

Definition 8

Physical quantities that can take on an exclusively discrete series of values \u200b\u200bare called quantized.

Definition 9

Elementary charge e represents a quantum, that is, the smallest possible portion of an electric charge.

Definition 10

The fact of the existence in modern physics of elementary particles of the so-called quarks - particles with fractional charge ± 1 3 e and ± 2 3 e.

However, scientists did not manage to observe quarks in a free state.

Definition 11

To detect and measure electric charges in laboratory conditions, an electrometer is usually used - an instrument consisting of a metal rod and an arrow that can rotate around a horizontal axis (Fig. 1. 1. 1).

The arrowhead is insulated from the metal housing. Contacting the rod of the electrometer, the charged body provokes the distribution of electric charges of the same sign along the rod and arrow. The impact of the forces of electrical repulsion becomes the cause of the deflection of the arrow at a certain angle, which can be used to determine the charge transferred to the rod of the electrometer.

Picture 1 . one . one . Charge transfer from a charged body to an electrometer.

An electrometer is a rather crude instrument. Its sensitivity does not allow studying the forces of interaction of charges. In 1785, the law of interaction of stationary charges was first discovered. The pioneer was the French physicist C. Coulomb. In his experiments, he measured the forces of attraction and repulsion of charged balls with the help of a device designed by him for measuring electric charge - a torsion balance (Fig. 1. 1. 2), which has an extremely high sensitivity. The balance beam was rotated by 1 ° under the action of a force of approximately 10 - 9 N.

The idea of \u200b\u200bmeasurements was based on the physicist's conjecture that when a charged ball comes into contact with the same uncharged one, the existing charge of the former will be divided into equal parts between the bodies. Thus, a method was obtained to change the charge of the ball by a factor of two or more.

Definition 12

Pendant in his experiments measured the interaction between balls, the dimensions of which were much smaller than the distance separating them, because of which they could be neglected. Such charged bodies are usually called point charges.

Picture 1 . one . 2. Pendant's device.

Picture 1 . one . 3. Forces of interaction of like and unlike charges.

Based on many experiences, Coulomb established the following law:

Definition 13

The forces of interaction of stationary charges are directly proportional to the product of charge moduli and inversely proportional to the square of the distance between them: F \u003d k q 1 q 2 r 2.

The forces of interaction are repulsive forces with the same signs of charges and forces of attraction with different signs (Fig. 1. 1. 3), and also obey Newton's third law:
F 1 → \u003d - F 2 →.

Definition 14

Coulomb or electrostatic interaction is called the impact on each other of stationary electric charges.

Definition 15

The section of electrodynamics devoted to the study of the Coulomb interaction is called electrostatics.

Coulomb's law can be applied to point charged bodies. In practice, it is fully fulfilled if the dimensions of the charged bodies can be neglected due to the significantly greater distance between the objects of interaction.

The proportionality coefficient k in Coulomb's law depends on the choice of the system of units.

In the international system C And the unit of measurement of the electric charge is the coulomb (K l).

Definition 16

Pendant - This is a charge passing through the cross-section of a conductor in 1 s at a current of 1 A. The unit of current (ampere) in C And is, along with the units of length, time and mass, the main unit of measurement.

The coefficient k in the system C And in most cases is written as the following expression:

k \u003d 1 4 π ε 0.

In which ε 0 \u003d 8, 85 · 10 - 12 K l 2 N · m 2 is an electrical constant.

In the C And system, the elementary charge e is equal to:

e \u003d 1.602177 10 - 19 K l ≈ 1.6 10 - 19 K l.

Based on experience, we can say that the forces of the Coulomb interaction obey the principle of superposition.

Theorem 1

If a charged body interacts simultaneously with several charged bodies, then the resulting force acting on this body is equal to the vector sum of the forces acting on this body from all other charged bodies.

Figure 1. one . 4, the principle of superposition is explained using the example of the electrostatic interaction of three charged bodies.

Picture 1 . one . four . Superposition principle of electrostatic forces F → \u003d F 21 → + F 31 →; F 2 → \u003d F 12 → + F 32 →; F 3 → \u003d F 13 → + F 23 →.

Picture 1 . one . five . Model of interaction of point charges.

Although the principle of superposition is a fundamental law of nature, its use requires some caution when applied to the interaction of charged bodies of finite dimensions. An example of such is two conducting charged balls 1 and 2. If one more charged ball is brought to a similar system, consisting of two balls with a charge, then the interaction between 1 and 2 will undergo changes due to the redistribution of charges.

The superposition principle assumes that the forces of electrostatic interaction between any two bodies do not depend on the presence of other bodies with a charge, provided that the distribution of charges is fixed (given).

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