What is the rest mass of an electron? What does an electron consist of? Electron mass and charge

Electron. Education and structure of the electron. Magnetic monopole of an electron.

(continuation)

Part 4. The structure of the electron.

4.1. An electron is a two-component particle, which consists only of two super-dense (condensed, concentrated) fields - electric field-minus and magnetic field-N. In this case:

a) electron density is the maximum possible in Nature;

b) electron dimensions (D = 10 -17 cm or less) - minimal in Nature;

c) in accordance with the requirement of minimizing energy, all particles - electrons, positrons, particles with a fractional charge, protons, neutrons, etc. must have (and have) a spherical shape;

d) for still unknown reasons, regardless of the energy value of the “parent” photon, absolutely all electrons (and positrons) are born absolutely identical in their parameters (for example, the mass of absolutely all electrons and positrons is 0.511 MeV).

4.2. “It has been reliably established that the magnetic field of an electron is the same integral property as its mass and charge. The magnetic fields of all electrons are the same, as are their masses and charges.” (c) This automatically allows us to make an unambiguous conclusion about the equivalence of the mass and charge of the electron, that is: the mass of the electron is the equivalent of the charge, and vice versa - the charge of the electron is the equivalent of the mass (for positron - similarly).

4.3. This equivalence property also applies to particles with fractional charges (+2/3) and (-1/3), which are the basis of quarks. That is: the mass of a positron, electron and all fractional particles is the equivalent of their charge, and vice versa - the charges of these particles are the equivalent of mass. Therefore, the specific charge of the electron, positron and all fractional particles is the same (const) and is equal to 1.76 * 10 11 Kl/kg.

4.4. Because elementary quantum of energy is automatically an elementary quantum of mass, then the mass of the electron (taking into account the presence of fractional particles 1/3 and 2/3) must have values , multiples of the masses of three negative half-quanta. (See also “Photon. Photon structure. Principle of movement. paragraph 3.4.)

4.5. Determining the internal structure of an electron is very difficult for many reasons; however, it is of significant interest to consider, at least to a first approximation, the influence of two components (electric and magnetic) on the internal structure of the electron. See fig. 7.

Fig.7. Internal structure electron, options:

Option #1. Each pair of negative half-quantum lobes forms "microelectrons", which then form an electron. In this case, the number of “microelectrons” must be a multiple of three.

Option #2. An electron is a two-component particle, which consists of two docked independent hemispherical monopoles - electric (-) and magnetic (N).

Option #3. An electron is a two-component particle, which consists of two monopoles - electric and magnetic. In this case, a spherical magnetic monopole is located at the center of the electron.

Option number 4. Other options.

Apparently, an option can be considered when electric (-) and magnetic fields (N) can exist inside an electron not only in the form of compact monopoles, but also in the form of a homogeneous substance, that is, form a practically structureless substance? crystalline? homogeneous? particle. However, this is highly doubtful.

4.6. Each of the options proposed for consideration has its own advantages and disadvantages, for example:

a) Options No. 1. Electrons of this design make it possible to easily form fractional particles with a mass and charge that is a multiple of 1/3, but at the same time they make it difficult to explain the electron’s own magnetic field.

b) Option No. 2. This electron, when moving around the nucleus of an atom, is constantly oriented towards the nucleus with its electric monopole and therefore can have only two options for rotation around its axis - clockwise or counterclockwise (Pauli exclusion?), etc.

4.7. When considering the indicated (or newly proposed) options, it is imperative to take into account the actual properties and characteristics of the electron, as well as take into account a number of mandatory requirements, for example:

Presence of an electric field (charge);

Presence of a magnetic field;

Equivalence of some parameters, for example: the mass of an electron is equivalent to its charge and vice versa;

The ability to form fractional particles with mass and charge multiples of 1/3;

Availability of a set quantum numbers, back, etc.

4.8. The electron appeared as a two-component particle, in which one half (1/2) is a densified electric field-minus (electric monopole-minus), and the second half (1/2) is a densified magnetic field (magnetic monopole-N). However, it should be kept in mind that:

Electric and magnetic fields at certain conditions can generate each other (turn into each other);

An electron cannot be a single-component particle and consist 100% of a minus field, since a singly charged minus field will decay due to repulsive forces. That is why there must be a magnetic component inside the electron.

4.9. Unfortunately, it is not possible in this work to conduct a complete analysis of all the advantages and disadvantages of the proposed options and choose the only correct option for the internal structure of the electron.

Part 5. “Wave properties of the electron.”

5.1. “By the end of 1924. the point of view according to which electromagnetic radiation behaves partly like waves and partly like particles became generally accepted... And it was at this time that the Frenchman Louis de Broglie, who was a graduate student at that time, had a brilliant idea: why couldn’t the same thing be for substance? Louis de Broglie did the opposite work on particles to what Einstein did on light waves. Einstein related electromagnetic waves to particles of light; de Broglie connected the movement of particles with the propagation of waves, which he called waves of matter. De Broglie's hypothesis was based on the similarity of equations describing the behavior of light rays and particles of matter, and was purely theoretical in nature. Experimental facts were required to confirm or refute it.” (c)

5.2. “In 1927, American physicists K. Davisson and K. Germer discovered that when electrons are “reflected” from the surface of a nickel crystal, maxima appear at certain angles of reflection. Similar data (the appearance of maxima) were already available from the observation of diffraction of X-ray waves on crystal structures. Therefore, the appearance of these maxima in reflected electron beams could not be explained in any other way except on the basis of ideas about waves and their diffraction. Thus, the wave properties of particles—electrons (and de Broglie’s hypothesis) were proven by experiment.”(c)

5.3. However, consideration of the process of the emergence of corpuscular properties of a photon outlined in this work (see Fig. 5.) allows us to draw quite unambiguous conclusions:

a) as the wavelength decreases from 10 -4 up to 10 - 10 (C)(C)(C)(C)(C) see the photon's electric and magnetic fields become denser

(C)(C)(C)(C)(C)(C)(C)(C)(C)(C) b) when the electric and magnetic fields become denser at the “dividing line,” a rapid increase in the “density” of the fields begins, and already in the X-ray range the field density is comparable to the density of an “ordinary” particle.

c) therefore, an X-ray photon, when interacting with an obstacle, is no longer reflected from the obstacle as a wave, but begins to bounce off it as a particle.

5.4. That is:

a) already in the soft X-ray range electromagnetic fields photons have become so dense that it is very difficult to detect their wave properties. Quote: “The shorter the wavelength of a photon, the more difficult it is to detect the properties of a wave and the more pronounced the properties of a particle.”

b) in the hard X-ray and gamma ranges, photons behave like 100% particles, and it is almost impossible to detect wave properties in them. That is: an x-ray and gamma photon completely loses the properties of a wave and turns into one hundred percent particle. Quote: “The energy of quanta in the X-ray and gamma range is so high that the radiation behaves almost entirely like a stream of particles” (c).

c) therefore, in experiments on the scattering of an X-ray photon from the surface of a crystal, it was no longer a wave, but an ordinary particle that bounced off the surface of the crystal and repeated the structure of the crystal lattice.

5.5. Before the experiments of K. Davisson and K. Germer, there were already experimental data on the observation of diffraction of X-ray waves on crystal structures. Therefore, having obtained similar results in experiments with the scattering of electrons on a nickel crystal, they automatically attributed wave properties to the electron. However, an electron is a “solid” particle that has a real rest mass, dimensions, etc. It is not the electron-particle that behaves like a photon-wave, but the X-ray photon has (and exhibits) all the properties of a particle. It is not the electron that is reflected from the obstacle as a photon, but the X-ray photon that is reflected from the obstacle as a particle.

5.6. Therefore: the electron (and other particles) did not have, does not, and cannot have any “wave properties”. And there are no prerequisites, much less opportunities, for changing this situation.

Part 6. Conclusions.

6.1. The electron and positron are the first and fundamental particles, the presence of which determined the appearance of quarks, protons, hydrogen and all other elements of the periodic table.

6.2. Historically, one particle was called an electron and given a minus sign (matter), and the other was called a positron and given a plus sign (antimatter). “They agreed to consider the electric charge of an electron negative in accordance with an earlier agreement to call the charge of electrified amber negative” (c).

6.3. An electron can appear (appear = born) only in a pair with a positron (electron-positron pair). The appearance in Nature of at least one “unpaired” (single) electron or positron is a violation of the law of conservation of charge, the general electrical neutrality of matter, and is technically impossible.

6.4. The formation of an electron-positron pair in the Coulomb field of a charged particle occurs after the division of elementary photon quanta in the longitudinal direction into two component parts: negative - from which a minus particle (electron) is formed and positive - from which a plus particle (positron) is formed. The division of an electrically neutral photon in the longitudinal direction into two parts absolutely equal in mass, but different in charges (and magnetic fields) is a natural property of the photon, resulting from the laws of charge conservation, etc. The presence “inside” the electron of even insignificant amounts of “plus particles” , and “inside” the positron - the “minus particle” - is excluded. The presence of electrically neutral “particles” (scraps, pieces, fragments, etc.) of the mother photon inside the electron and proton is also excluded.

6.5. For unknown reasons, absolutely all electrons and positrons are born as standard “maximum-minimum” particles (that is, they cannot be larger and cannot be smaller in mass, charge, dimensions and other characteristics). The formation of any smaller or larger plus particles (positrons) and minus particles (electrons) from electromagnetic photons is excluded.

6.6. The internal structure of an electron is uniquely predetermined by the sequence of its appearance: the electron is formed as a two-component particle, which is 50% a densified electric field-minus (electric monopole-minus), and 50% a densified magnetic field (magnetic monopole-N). These two monopoles can be considered as differently charged particles, between which forces of mutual attraction (adhesion) arise.

6.7. Magnetic monopoles exist, but not in free form, but only as components of an electron and a positron. In this case, the magnetic monopole (N) is an integral part of the electron, and the magnetic monopole (S) is an integral part of the positron. The presence of a magnetic component “inside” the electron is mandatory, since only a magnetic monopole-(N) can form a very strong (and unprecedented in strength) bond with a singly charged electric monopole-minus.

6.8. Electrons and positrons have the greatest stability and are particles whose decay is theoretically and practically impossible. They are indivisible (in terms of charge and mass), that is: spontaneous (or forced) division of an electron or positron into several calibrated or “different-sized” parts is excluded.

6.9. An electron is eternal and it cannot “disappear” until it encounters another particle that has electric and magnetic charges equal in magnitude but opposite in sign (positron).

6.10. Since from electromagnetic waves If only two standard (calibrated) particles can appear: an electron and a positron, then on their basis only standard quarks, protons and neutrons can appear. Therefore, all visible (baryonic) matter of ours and all other universes consists of identical chemical elements(mendeleev’s table) and the same rules apply everywhere physical constants And fundamental laws, similar to “our” laws. The appearance at any point of infinite space of “other” elementary particles and “other” chemical elements is excluded.

6.11. All visible matter in our Universe was formed from photons (presumably from the microwave range) according to the only possible scheme: photon → electron-positron pair → fractional particles → quarks, gluon → proton (hydrogen). Therefore, all “solid” matter of our Universe (including Homo sapiens) is condensed electric and magnetic fields of photons. There were no other “matter” for its formation in the Cosmos, there is not and there cannot be.

P.S. Is the electron inexhaustible?

How can one experimentally determine the mass of an electron or proton by accelerating a charged particle along a known distance in a known uniform electric field and measuring its final velocity? As is known, if a body travels a path d in the direction of force F, then the work Fd spent on moving the body is equal to the increment of its kinetic energy. If movement begins from a state of rest, then this work is also equal to the final kinetic energy of the body: Fd= mv 2 /2

Thus, if F, d and v are known, then the mass m can be found from here.

In the experiments about which we'll talk, the charged particles of interest to us are accelerated by a uniform force field between two charged metal plates. Knowing the distance between the plates and the number of batteries charging them, it is possible to determine the electric force applied to each elementary charge. Experiments are carried out in a vacuum to eliminate air resistance that occurs in micro-micro balances. In addition, since protons and electrons are more than 10 11 times lighter than the plastic balls used in micro-micro balances, gravitational force can be neglected in these experiments compared to electrical forces.
A certain amount of hydrogen undergoes ionization near a pair of charged plates (Fig.), after which some of the ions enter at a negligible speed through a small hole into the space between the plates. As the ions move from one plate to another, the electric field accelerates the ions, giving them a final kinetic energy mv 2 /2. The right plate has a small hole through which some of the ions can enter the 0.50 m long chamber (Fig.). This chamber is made of a conductive material, and since there is no electric field, the ions travel its entire length without changing their speed. It takes the ion only a few microseconds to travel this entire path (1 μs = 10 -6 s). Although this period of time is very short, it can still be accurately measured using a special measuring device. This allows the terminal velocity v of the ion to be accurately determined.
To measure the time it takes ions to travel through a long chamber from one end to the other, it is necessary to note the moment when a given ion leaves this point on the left, and the time for the same ion to reach the far end on the right. To notice the time when a given ion enters a long chamber, we place a pair of small deflecting plates near the entrance (Fig.). With their help, you can control the direction of the hydrogen ion beam. When the deflector plates are charged, the hydrogen ions are subject to a lateral electrical force that deflects them away from their path. If the deflection plates are then discharged, then only those ions that have just or later entered the chamber will move along the longitudinal axis of the chamber; therefore, the first ions to pass through the hole at the far end will be those that have traveled the entire distance of 0.50 m in the time since the plates were discharged. The arrival of these ions is detected by a sensing element placed behind the hole.
To measure the time interval from the moment the plates are discharged until the first ions arrive at the receiving element, the deflection plates in the chamber are connected to the vertical deflection plates of the oscilloscope (Fig.). The moment of discharge of the plates in the long chamber is marked by a peak on the curve drawn on the screen of the oscilloscope. The sensing element at the far end of the long chamber is connected to the same vertical deflection plates of the oscilloscope (the electrical connections at both ends of the chamber are made exactly the same). When the ion beam hits the receiving element, a second peak appears on the oscilloscope screen (Fig.). The two peaks appear in different places on the screen because they originated in different times. During the intermediate time between these two moments, the sweep circuit of the oscilloscope causes the electron beam to move horizontally on the screen. The electron beam in an oscilloscope travels the distance between two peaks in the same time as it takes hydrogen ions to travel 0.50 m in the chamber.

In modern oscilloscopes, the sweep circuit can cause the electron beam on the tube screen to move horizontally from one end to the other in a few hundredths of a microsecond. To measure ion velocity, the sweep circuit is adjusted to sweep the entire curve in 5 microseconds. Then the two peaks on the oscilloscope screen will be noticeably separated. By measuring the distance between the peaks, the time it takes for the beam to cross the long chamber is determined. Find the time interval from the moment when the beam is able to move straight forward until the moment it hits the receiving element, with an accuracy of 0.01 microseconds. In the case of hydrogen ions and a 90-volt battery providing an accelerating electrical force, the time of flight is 3.82 microseconds. From this we can calculate the velocity v of the ions in the long chamber. It is equal to 0.50 m/(3.82*10 -6 s) = = 1.31*10 5 m/s.
On the other hand, the plates here are exactly three times further apart than in the micro-microbalances in which Millikan’s experiment was carried out; In addition, it uses three times fewer of the same batteries. Since the force per elementary charge is proportional to the number of identical batteries and inversely proportional to the distance between the plates, each elementary charge must now be acted upon by nine times less force, i.e. 1/9 * 10 -14).
If we assume that one hydrogen atom carries one elementary charge, then each ion between the plates experiences the force just expressed. Moving from one plate to another, the ion travels a path of 9.3 10 -3 m in the direction of the force, so the work done to move the ion is equal to Fd = 1/9(1.4*10 -14 N)*(9.3 10 -3 m)= 1.4 10 -17 J. Therefore,
mv/2=m (1.3*10 5 m/s) 2 /2=1.4 *10 -17 J.
From here, for the mass of the hydrogen ion m we find
m= 1.7 *10 -27 kg.

But this value is well known to us. Within the accuracy of our measurements, it coincides with the mass of the hydrogen atom.
Now we can summarize. If a hydrogen ion is charged once, then its mass is almost equal to the mass of a hydrogen atom. One can even go a step further and argue that the hydrogen ion is indeed a unit charge carrier and that its mass is practically equal to the mass of the atom. This must be correct, since assuming that the ion carries more charge will lead to an absurd result. For example, if an ion carries two elementary charges, then the actual value mv 2 /2 should be twice the value we accepted. Since we measured v, this can only mean that the ion's mass is twice what we found. Such a hydrogen ion would have a mass twice the mass of the atom of which it is a fragment. This conclusion is so implausible that we reject it.

Previously, there were indications that electrons are building blocks found in all atoms. Apparently, a hydrogen ion is a hydrogen atom that has lost one electron. In addition, neither in this nor in other experiments have we ever encountered a positively charged fragment of hydrogen with two positive elementary charges. This is one of many proofs that the positively charged hydrogen ion is the ultimate building block. This is a proton. When hydrogen splits into charged particles, then, as has just been established, the proton accounts for almost the entire mass of the atom. Therefore the electrons must be very light. You can use the same instruments to measure the mass of the electron and thus verify this conclusion.

This term has other meanings, see Electron (meanings). "Electron 2" "Electron" series of four Soviet artificial satellites Earth launched in 1964. Purpose ... Wikipedia

Electron- (Novosibirsk, Russia) Hotel category: 3 star hotel Address: 2nd Krasnodonsky Lane ... Hotel catalog

- (symbol e, e), first element. h tsa discovered in physics; mater. the carrier of the smallest mass and the smallest electric power. charge in nature. E. component of atoms; their number in neutr. atom equals at. number, i.e. the number of protons in the nucleus. Charge (e) and mass... ... Physical encyclopedia

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Electron- (e, e) (from the Greek elektron amber; a substance that is easily electrified by friction), a stable elementary particle with a negative electric charge e=1.6´10 19 C and a mass of 9´10 28 g. Belongs to the class of leptons. Discovered by an English physicist... ... Illustrated encyclopedic dictionary

- (e e), stable negatively charged elementary particle with spin 1/2, mass approx. 9.10 28 g and magnetic moment, equal to the Bohr magneton; belongs to leptons and participates in electromagnetic, weak and gravitational interactions.... ...

- (designation e), a stable ELEMENTARY PARTICLE with a negative charge and a rest mass of 9.1310 31 kg (which is 1/1836 of the mass of a PROTON). Electrons were discovered in 1879 by the English physicist Joseph Thomson. They move around the CORE,... ... Scientific and technical encyclopedic dictionary

Exist., number of synonyms: 12 delta electron (1) lepton (7) mineral (5627) ... Dictionary of synonyms

An artificial Earth satellite created in the USSR to study radiation belts and the Earth's magnetic field. They were launched in pairs, one along a trajectory lying below and the other above the radiation belts. In 1964, 2 pairs of Electrons were launched... Big Encyclopedic Dictionary

ELECTRON, ELECTRON, husband. (Greek elektron amber). 1. A particle with the smallest negative electric charge, forming an atom in combination with a proton (physical). The movement of electrons creates an electric current. 2. only units. Lightweight magnesium alloy,... ... Dictionary Ushakova

ELECTRON, a, m. (special). An elementary particle with the smallest negative electrical charge. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

Books

• Electron. Energy of Space, Landau Lev Davidovich, Kitaigorodsky Alexander Isaakovich. Laureate's books Nobel Prize Lev Landau and Alexander Kitaigorodsky - texts that overturn the philistine idea of ​​the world around us. Most of us are constantly faced with...
• Electron Space Energy, Landau L., Kitaigorodsky A.. Books by Nobel Prize winner Lev Landau and Alexander Kitaigorodsky are texts that overturn the philistine idea of ​​the world around us. Most of us, constantly faced with...

It is known that electrons have a negative charge. But how can one be sure that the mass of the electron and its charge are constant for all these particles? You can check this only by catching it on the fly. Having stopped, it gets lost among the molecules and atoms that make up laboratory equipment. The process of understanding the microcosm and its particles has come a long way: from the first primitive experiments to the latest developments in the field of experimental atomic physics.

First information about electrons

One hundred and fifty years ago electrons were not known. The first signal indicating the existence of the “building blocks” of electricity were experiments in electrolysis. In all cases, each charged particle of matter carried a standard electric charge, which had the same value. In some cases the amount of charge doubled or tripled, but always remained a multiple of one minimum charge amount.

Experiments by J. Thompson

In Cavendish's laboratory, J. Thomson conducted an experiment that actually proved the existence of particles of electricity. To do this, the scientist examined the radiation emanating from the cathode tubes. In the experiment, the rays were repelled from a negatively charged plate and attracted to a positively charged one. The hypothesis about the constant presence of certain electrical particles in the electric field was confirmed. Their speed of movement was comparable to the speed of light. The electric charge in terms of the mass of the particle turned out to be incredibly large. From his observations, Thompson drew several conclusions that were subsequently confirmed by other studies.

Thompson's conclusions

1. Atoms can be broken apart when bombarded by faster particles. At the same time, negatively charged corpuscles escape from the middle of the atoms.
2. All charged particles have the same mass and charge, regardless of the substance from which they were derived.
3. The mass of these particles is much less than the mass of the lightest atom.
4. Each particle of a substance carries the smallest possible fraction of an electric charge, less than which does not exist in nature. Any charged body carries a whole number of electrons.

Detailed experiments made it possible to calculate the parameters of mysterious microparticles. As a result, it was found that open charged corpuscles are indivisible atoms of electricity. Subsequently, they were given the name electrons. It came from Ancient Greece and turned out to be appropriate for describing the newly discovered particle.

Direct measurement of electron velocity

Since there is no way to see the electron, the experiments necessary to measure the basic quantities of this elementary particle are carried out using fields - electromagnetic and gravitational. If the first affects only the charge of the electron, then with the help of subtle experiments, taking into account the gravitational effect, it was possible to approximately calculate the mass of the electron.

Electron gun

The very first measurements of electron masses and charges were made using an electron gun. The deep vacuum in the gun body allows electrons to rush in a narrow beam from one cathode to another.

Electrons are forced to pass through narrow holes twice at a constant speed v. A process occurs similar to how a stream from a garden hose enters a hole in a fence. Portions of electrons fly along the tube at a constant speed. It has been experimentally proven that if the voltage applied to the electron gun is 100 V, then the speed of the electron will be calculated as 6 million m/s.

Experimental findings

Direct measurement of the electron velocity shows that, regardless of what materials the gun is made of and what the potential difference is, the relation e/m = const holds.

This conclusion was made already at the beginning of the 20th century. At that time they did not yet know how to create homogeneous beams of charged particles; other devices were used for experiments, but the result remained the same. The experiment allowed us to draw several conclusions. The ratio of the charge of an electron to its mass has the same value for electrons. This makes it possible to draw a conclusion about the universality of the electron as a component of any matter in our world. At very high speeds, the value of e/m turns out to be less than expected. This paradox is fully explained by the fact that at high speeds comparable to the speed of light, the mass of the particle increases. The boundary conditions of the Lorentz transformations indicate that at the speed of the body, equal speed light, the mass of this body becomes infinite. A noticeable increase in the electron mass occurs in complete agreement with the theory of relativity.

Electron and its rest mass

The paradoxical conclusion that the mass of the electron is not constant leads to several interesting conclusions. In the normal state, the rest mass of the electron does not change. It can be measured based on various experiments. Currently, the mass of the electron has been repeatedly measured and is 9.10938291(40)·10⁻³¹ kg. Electrons with such a mass enter into chemical reactions, form the movement of electric current, and are captured by the most precise instruments that record nuclear reactions. A noticeable increase in this value is possible only at speeds close to the speed of light.

Electrons in crystals

Physics solid is a science that makes observations of the behavior of charged particles in crystals. The result of numerous experiments was the creation of a special quantity that characterizes the behavior of an electron in force fields crystalline substances. This is the so-called effective mass of the electron. Its value is calculated based on the fact that the movement of an electron in a crystal is subject to additional forces, the source of which is the crystal lattice itself. Such motion can be described as standard for a free electron, but when calculating the momentum and energy of such a particle, one should take into account not the rest mass of the electron, but the effective one, the value of which will be different.

Momentum of an electron in a crystal

The state of any free particle can be characterized by the magnitude of its momentum. Since the value of the momentum has already been determined, then, according to the uncertainty principle, the coordinates of the particle seem to be blurred throughout the crystal. The probability of encountering an electron at any point in the crystal lattice is almost the same. The momentum of an electron characterizes its state in any coordinate of the energy field. Calculations show that the dependence of the energy of an electron on its momentum is the same as that of a free particle, but at the same time the mass of the electron can take on a value that differs from the usual one. In general, the electron energy, expressed in terms of momentum, will have the form E(p)=p 2 /2m*. In this case, m* is the effective mass of the electron. Practical Application the effective mass of an electron is extremely important in the development and study of new semiconductor materials used in electronics and microtechnology.

The mass of an electron, like any other quasiparticle, cannot be characterized by standard characteristics suitable in our Universe. Any characteristic of a microparticle can surprise and question all our ideas about the world around us.

Based on the laws of electrolysis established by M. Faraday, the Irish scientist D. Stoney put forward the hypothesis that there is an elementary charge inside the atom. And in 1891 Stoney proposed calling this charge an electron. The amount of charge on an electron is often denoted e or .

The laws of electrolysis are not yet proof of the existence of the electron as an elementary electric charge. Thus, there was an opinion that all monovalent ions can have different charges, and their average value is equal to the charge of the electron. To prove the existence of an elementary charge in nature, it was necessary to measure the charges of individual ions, and not the total amount of electricity. In addition, the question remained open as to whether the charge was associated with any particle of matter. A significant contribution to solving these issues was made by J. Perrin and J. Thomson. They investigated the laws of motion of particles of cathode rays in electric and magnetic fields. Perrin showed that cathode rays are a stream of particles that carry a negative charge. Thomson established that all these particles have equal relations charge to mass:

In addition, Thomson showed that for different gases the ratio of cathode ray particles is the same, and does not depend on the material from which the cathode was made. From this we could conclude that the particles that make up the atoms of different elements are the same. Thomson himself concluded that atoms are divisible. Particles with a negative charge and very small mass can be torn out of an atom of any substance. All these particles have the same mass and the same charge. Such particles were called electrons.

Experiments of Millikan and Ioffe

The American scientist R. Millikan experimentally proved that an elementary charge exists. In his experiments, he measured the speed of movement of oil droplets in a uniform electric field, which was created between two electric plates. The drop became charged when it collided with the ion. The speeds of movement of a drop without a charge and the same drop after a collision with an ion (which acquired a charge) were compared. Knowing the field strength between the plates, the charge of the drop was calculated.

Millikan's experiments were repeated by A.F. Ioffe. He used metal specks instead of drops of oil. By changing the field strength between the plates, Ioffe achieved equality between the gravity force and the Coulomb force, while the dust particle remained motionless. The speck of dust was illuminated with ultraviolet light. At the same time, its charge changed; to balance the force of gravity, it was necessary to change the field strength. Based on the obtained intensity values, the scientist judged the ratio of the electrical charges of the dust particle.

In the experiments of Millikan and Ioffe it was shown that the charges of dust particles and drops always changed abruptly. The minimum change in charge was equal to:

The electric charge of any charged body is equal to an integer and is a multiple of the charge of the electron. There is now an opinion that there are elementary particles- quarks that have a fractional charge ().

Thus, the electron charge is considered equal to:

Examples of problem solving

EXAMPLE 1

Exercise	In a flat capacitor, the distance between the plates of which is equal to d, a drop of oil is motionless, its mass is m. How many excess electrons are there on it if the potential difference between the plates is U?
Solution	This problem considers an analogue of Millikan's experiment. A drop of oil is acted upon by two forces that cancel each other out. These are gravity and Coulomb force (Fig. 1). Since the field inside a flat capacitor can be considered uniform, we have: where E is the electrostatic field strength in the capacitor. The magnitude of the electrostatic force can be found as: Since the particle is in equilibrium and does not move, then according to Newton’s Second Law we obtain: From formula (1.3) we express the charge of the particle: Knowing the value of the electron charge (), the number of excess electrons (creating the charge of the drop), we find it as:
Answer

EXAMPLE 2

Exercise	How many electrons did the drop lose after irradiation with ultraviolet light (see Example 1), if the acceleration with which it began to move downward is equal to a?
Solution	We write Newton's second law for this case as: The coulomb force changed because the particle charge changed after irradiation: In accordance with Newton's second law we have: