Angina

The use of magnets in various fields of activity of modern society. Abstracts

It will be useful to provide a few definitions and explanations at the very beginning of the work.

If, in some place, a force acts on moving bodies with a charge that does not act on stationary or chargeless bodies, then they say that there is a force in this place. magnetic field one of the more general forms electromagnetic field .

There are bodies capable of creating a magnetic field around themselves (and such a body is also affected by the force of a magnetic field); they are said to be magnetized and have a magnetic moment, which determines the body’s ability to create a magnetic field. Such bodies are called magnets .

It should be noted that different materials react differently to an external magnetic field.

There are materials that weaken the effect of the external field within themselves paramagnets and enhancing the external field within themselves diamagnetic materials .

There are materials with a huge ability (thousands of times) to enhance the external field inside themselves - iron, cobalt, nickel, gadolinium, alloys and compounds of these metals, they are called ferromagnets .

There are materials among ferromagnets that, after being exposed to a sufficiently strong external magnetic field, become magnets themselves. hard magnetic materials.

There are materials that concentrate an external magnetic field and, while it is active, behave like magnets; but if the external field disappears they do not become magnets soft magnetic materials

INTRODUCTION

We are accustomed to the magnet and treat it a little condescendingly as an outdated attribute of school physics lessons, sometimes not even suspecting how many magnets there are around us. There are dozens of magnets in our apartments: in electric shavers, speakers, tape recorders, in watches, in jars of nails, finally. We ourselves are also magnets: the biocurrents flowing in us give birth around us a bizarre pattern of magnetic power lines. The earth we live on is a giant blue magnet. The sun is a yellow plasma ball, a magnet that is even more grandiose. Galaxies and nebulae, barely visible through telescopes, are magnets of incomprehensible size. Fusion, magnetodynamic generation of electricity, acceleration of charged particles in synchrotrons, lifting of sunken ships - all these are areas where enormous magnets of unprecedented size are required. The problem of creating strong, super-strong, ultra-strong and even stronger magnetic fields has become one of the main ones in modern physics and technology.

The magnet has been known to man since time immemorial. We have received mentions

about magnets and their properties in the works of Thales of Miletus (approx. 600 BC) and Plato (427,347 BC). The word magnet itself arose due to the fact that natural magnets were discovered by the Greeks in Magnesia (Thessaly).

Natural (or natural) magnets occur in nature in the form of deposits of magnetic ores. The largest known natural magnet is located at the University of Tartu. Its mass is 13 kg and it is capable of lifting a load of 40 kg.

Artificial magnets are magnets created by man based on various ferromagnets. So-called powder magnets (made of iron, cobalt and some other additives) can hold a load of more than 5,000 times their own weight.

There are artificial magnets of two different types:

Some so-called permanent magnets , made from magnetically hard materials. Their magnetic properties are not related to the use of external sources or currents.

Another type includes the so-called electromagnets with a core made of soft magnetic gland. The magnetic fields they create are mainly due to the fact that the wire of the winding surrounding the core passes electric current.

In 1600, a book by the royal physician W. Gilbert “On the Magnet, Magnetic Bodies and big magnet- Earth.” This essay was the first attempt at research known to us magnetic phenomena from the standpoint of science. This work contains the then available information about electricity and magnetism, as well as the results of the author’s own experiments.

Of everything that a person encounters, he first of all strives to derive practical benefit. The magnet did not escape this fate either.

In my work I will try to trace how magnets are used by humans not for war, but for peaceful purposes, including the use of magnets in biology, medicine, and in everyday life.

COMPASS, a device for determining horizontal directions on the ground. Used to determine the direction in which a ship, aircraft, or land vehicle is moving vehicle; the direction in which the pedestrian is walking; directions to some object or landmark. Compasses are divided into two main classes: magnetic compasses of the pointer type, which are used by topographers and tourists, and non-magnetic ones, such as the gyrocompass and radio compass.

By the 11th century. refers to the message of the Chinese Shen Kua and Chu Yu about the manufacture of compasses from natural magnets and their use in navigation. If

Magnets are mainly used in electrical engineering, radio engineering, instrument making, automation and telemechanics. Here, ferromagnetic materials are used for the manufacture of magnetic circuits, relays, etc. .

Electric machine generators and electric motors are rotational machines that convert either mechanical energy into electrical energy (generators) or electrical energy into mechanical energy (engines). The operation of generators is based on the principle electromagnetic induction: An electromotive force (EMF) is induced in a wire moving in a magnetic field. The operation of electric motors is based on the fact that a force acts on a current-carrying wire placed in a transverse magnetic field.

Magnetoelectric devices. Such devices use the force of interaction between the magnetic field and the current in the turns of the winding of the moving part, which tends to turn the latter.

Induction electricity meters. An induction meter is nothing more than a low-power AC electric motor with two windings - a current winding and a voltage winding. A conductive disk placed between the windings rotates under the influence of a torque proportional to the power consumed. This torque is balanced by currents induced in the disk by a permanent magnet, so that the rotation speed of the disk is proportional to the power consumption.

Electrical wrist watch powered by a miniature battery. They require far fewer parts to operate than mechanical watches; Thus, the circuit of a typical electric portable watch includes two magnets, two inductors and a transistor.

Dynamometer - mechanical or electrical appliance to measure the traction force or torque of a machine, machine tool or engine.

Brake dynamometers come in a variety of designs; These include, for example, the Prony brake, hydraulic and electromagnetic brakes.

An electromagnetic dynamometer can be made in the form of a miniature device suitable for measuring the characteristics of small-sized engines.

A galvanometer is a sensitive instrument for measuring weak currents. A galvanometer uses the torque produced by the interaction of a horseshoe-shaped permanent magnet with a small current-carrying coil (a weak electromagnet) suspended in the gap between the poles of the magnet. The torque, and therefore the deflection of the coil, is proportional to the current and the total magnetic induction in the air gap, so that the scale of the device is almost linear for small deflections of the coil. Devices based on it are the most common type of devices.

The magnetic properties of a substance are found wide application in science and technology as a means of studying the structure of various bodies. This is how science came into being:

Magnetochemistry is a branch of physical chemistry that studies the relationship between magnetic and chemical properties substances; In addition, magnetochemistry studies the influence of magnetic fields on chemical processes. Magnetochemistry is based on modern physics magnetic phenomena. Studying the relationship between magnetic and chemical properties makes it possible to clarify the features chemical structure substances.

Magnetic flaw detection, a method of searching for defects based on the study of magnetic field distortions that occur at defects in products made of ferromagnetic materials.

Particle accelerator, a facility in which, using electric and magnetic fields, directed beams of electrons, protons, ions and other charged particles with energy significantly exceeding thermal energy are obtained.

Modern accelerators use numerous and varied types of technology, incl. powerful precision magnets.

Accelerators play an important practical role in medical therapy and diagnostics. Many hospitals around the world now have small electron linear accelerators at their disposal that generate intense X-rays used to treat tumors. To a lesser extent, cyclotrons or synchrotrons generating proton beams are used. The advantage of protons in tumor therapy over x-ray radiation consists of a more localized energy release. That's why proton therapy It is especially effective in the treatment of tumors of the brain and eyes, when damage to surrounding healthy tissue should be as minimal as possible.

Representatives various sciences take magnetic fields into account in their research. Physicist measures magnetic fields of atoms and elementary particles, an astronomer studies the role of cosmic fields in the process of the formation of new stars, a geologist uses anomalies in the Earth’s magnetic field to find deposits of magnetic ores, and recently biology has also been actively involved in the study and use of magnets.

Biological science of the first half of the 20th century confidently described vital signs, without taking into account the existence of any magnetic fields. Moreover, some biologists considered it necessary to emphasize that even a strong artificial magnetic field has no effect on biological objects.

In encyclopedias about the influence of magnetic fields on biological processes nothing was said. Every year, isolated positive considerations about one or another appeared in the scientific literature around the world. biological effect magnetic fields. However, this weak trickle could not melt the iceberg of mistrust even in the formulation of the problem itself... And suddenly the trickle turned into a stormy stream. The avalanche of magnetobiological publications, as if falling from some peak, has been steadily increasing since the early 60s and drowning out skeptical statements.

From the alchemists of the 16th century to the present day, the biological effect of the magnet has found admirers and critics many times. Repeatedly over the course of several centuries, there have been ups and downs of interest in therapeutic effect magnet. With its help they tried to treat (and not unsuccessfully) nervous diseases, toothache, insomnia, pain in the liver and stomach - hundreds of diseases.

For medicinal purposes, magnets began to be used, probably, earlier than for determining the cardinal directions.

As a local external remedy and as an amulet, the magnet enjoyed great success among the Chinese, Hindus, Egyptians, Arabs, Greeks, Romans, etc. Oh him medicinal properties The philosopher Aristotle and the historian Pliny mention in their works.

In the second half of the 20th century, magnetic bracelets became widespread, having a beneficial effect on patients with blood pressure(hypertension and hypotension).

Except permanent magnets Electromagnets are also used. They are also used for wide range problems in science, technology, electronics, medicine ( nervous diseases, vascular diseases of the extremities, cardiovascular vascular diseases, cancer).

Most of all, scientists are inclined to think that magnetic fields increase the body's resistance.

There are electromagnetic blood velocity meters, miniature capsules that can be moved around with the help of external magnetic fields. blood vessels to expand them, take samples at certain parts of the path, or, conversely, locally remove various medications from the capsules.

Widespread magnetic method removing metal particles from the eye.

Most of us are familiar with the study of heart function using electrical sensors - an electrocardiogram. Electrical impulses generated by the heart create a magnetic field of the heart, which in max values is 10-6 of the strength of the Earth's magnetic field. The value of magnetocardiography is that it allows one to obtain information about the electrically “silent” areas of the heart.

It should be noted that biologists are now asking physicists to give a theory of the primary mechanism of the biological action of the magnetic field, and physicists in response are demanding from biologists more proven biological facts. It is obvious that close cooperation between various specialists will be successful.

An important link uniting magnetobiological problems is the reaction nervous system to magnetic fields. It is the brain that is the first to react to any changes in external environment. It is the study of its reactions that will be the key to solving many problems in magnetobiology.

Among the technological revolutions of the late 20th century, one of the most important is the transition of consumers to nuclear fuel. Once again, magnetic fields came into focus. Only they will be able to curb the wayward plasma in a “peaceful” thermonuclear reaction, which should replace the fission reactions of radioactive uranium and thorium nuclei.

What else would you burn? - the question that always torments energy workers is an obsessive refrain. For quite a long time, firewood helped us out, but it has low energy consumption, and therefore the wood-fired civilization is primitive. Our current wealth is based on the burning of fossil fuels, but the readily available reserves of oil, coal and natural gas slowly but surely they are drying up. Willy-nilly, we have to reorient the country's fuel and energy balance to something else. In the next century, the remains of organic fuel will have to be preserved for the raw materials needs of chemistry. And the main energy raw material, as is known, will be nuclear fuel.

The idea of magnetic thermal insulation of plasma is based on known property electrically charged particles moving in a magnetic field bend their trajectory and move along a spiral of field lines. This curvature of the trajectory in a non-uniform magnetic field leads to the fact that the particle is pushed into a region where the magnetic field is weaker. The task is to surround the plasma on all sides with a stronger field. This problem is being solved in many laboratories around the world. Magnetic confinement of plasma was discovered by Soviet scientists, who in 1950 proposed confining plasma in so-called magnetic traps (or, as they are often called, magnetic bottles).

An example of a very simple system for magnetically confining a plasma is a trap with magnetic plugs or mirrors (mirror trap). The system is a long pipe in which a longitudinal magnetic field is created. More massive windings are wound at the ends of the pipe than in the middle. This leads to the fact that the magnetic field lines at the ends of the pipe are denser and the magnetic field in these areas is stronger. Thus, a particle trapped in a magnetic bottle cannot leave the system, because it would have to cross the field lines and, due to the Lorentz force, “wind up” on them. On this principle, the huge magnetic trap of the Ogra-1 installation, launched at the Institute, was built atomic energy named after I.V. Kurchatov in 1958. The Ogra-1 vacuum chamber has a length of 19 m with an internal diameter of 1.4 m. The average diameter of the winding creating the magnetic field is 1.8 m, the field strength in the middle of the chamber is 0.5 T, in traffic jams 0.8 T.

The cost of electricity obtained from thermonuclear power plants will be very low due to the low cost of the feedstock (water). The time will come when power plants will generate literally oceans of electricity. With the help of this electricity, it will be possible, perhaps, not only to radically change the conditions of life on Earth - turn back rivers, drain swamps, water deserts - but also change the appearance of the environment outer space- populate and “revive” the Moon, surround Mars with an atmosphere.

One of the main difficulties on this path is the creation of a magnetic field of a given geometry and magnitude. Magnetic fields in modern thermonuclear traps are relatively small. However, if we take into account the enormous volumes of the chambers, the absence of a ferromagnetic core, as well as the special requirements for the shape of the magnetic field, which complicate the creation of such systems, we must admit that the existing traps are a great technical achievement.

Based on the above, we can conclude that at present there is no industry in which a magnet or the phenomenon of magnetism is not used.

Ш Magnetic storage media: VHS cassettes contain reels of magnetic tape. Video and audio information is encoded onto a magnetic coating on the tape. Also, in computer floppy disks and hard drives, data is recorded on a thin magnetic coating. However, storage media are not magnets in the strict sense, since they do not attract objects. The magnets in hard drives are used in drive and positioning motors.
Ш Credit, Debit, and ATM Cards: All of these cards have a magnetic stripe on one side. This band encodes the information needed to connect to a financial institution and link to their accounts.
Ш Conventional televisions and computer monitors: Televisions and computer monitors containing a cathode ray tube use an electromagnet to control a beam of electrons and form an image on the screen. Plasma panels and LCD monitors use different technologies.
Ш Loudspeakers and microphones: Most loudspeakers use a permanent magnet and a current coil to convert electrical energy (the signal) into mechanical energy (the movement that creates sound). The winding is wound on a coil, attached to a diffuser, and alternating current flows through it, which interacts with the field of a permanent magnet.
Ш Another example of the use of magnets in audio engineering is in the pickup head of an electrophone and in cassette recorders as an economical erasing head.
Ш Magnetic separator of heavy minerals
Ш Electric motors and generators: some electric motors(same as loudspeakers) are based on a combination of an electromagnet and a permanent magnet. They convert electrical energy into mechanical energy. A generator, on the other hand, converts mechanical energy into electrical energy by moving a conductor through a magnetic field.
Ш Transformers: Devices for transmitting electrical energy between two windings of wire that are electrically isolated but coupled magnetically.
Ш Magnets are used in polarized relays. Such devices remember their state when the power is turned off.
Ш Compasses: A compass (or marine compass) is a magnetized pointer that can rotate freely and is oriented in the direction of a magnetic field, most often the Earth's magnetic field.
Sh Art: Vinyl magnetic sheets can be attached to paintings, photographs and other decorative items, allowing them to be attached to refrigerators and other metal surfaces.
Ш Magnets are often used in toys. M-TIC uses magnetic bars connected to metal spheres
Ш Toys: Given their ability to resist gravity at close range, magnets are often used in children's toys with fun effects.
Ш Magnets can be used to make jewelry. Necklaces and bracelets can have a magnetic clasp, or can be made entirely from a series of linked magnets and black beads.
Ш Magnets can pick up magnetic objects (iron nails, staples, tacks, paper clips) that are either too small, difficult to reach, or too thin to handle with your fingers. Some screwdrivers are specially magnetized for this purpose.
Ш Magnets can be used in scrap metal processing to separate magnetic metals (iron, steel and nickel) from non-magnetic ones (aluminum, non-ferrous alloys, etc.). The same idea can be used in what is called a "Magnetic Test", in which the car body is examined with a magnet to identify areas repaired using fiberglass or plastic putty.
Sh Maglev: Magnetic levitation train driven and controlled by magnetic forces. Such a train, unlike traditional trains, does not touch the rail surface during movement. Since there is a gap between the train and the moving surface, friction is eliminated and the only braking force is the aerodynamic drag force.
Ш Magnets are used in furniture door locks.
Ш If magnets are placed in sponges, then these sponges can be used to wash thin sheet non-magnetic materials on both sides at once, and one side may be difficult to reach. This could be, for example, the glass of an aquarium or balcony.
Ш Magnets are used to transmit torque “through” a wall, which could be, for example, a sealed container of an electric motor. This is how the GDR toy “Submarine” was designed.
Ш Magnets together with a reed switch are used in special position sensors. For example, in refrigerator door sensors and security alarms.
Ш Magnets together with a Hall sensor are used to determine the angular position or angular velocity shaft
Ш Magnets are used in spark gaps to speed up arc extinction.
Ш Magnets are used for non-destructive testing using the magnetic particle method (MPC)
Ш Magnets are used to deflect beams of radioactive and ionizing radiation, for example during observation in cameras.
Ш Magnets are used in indicating instruments with a deflecting needle, for example, an ammeter. Such devices are very sensitive and linear.
Ш Magnets are used in microwave valves and circulators.
Ш Magnets are used as part of a deflecting system of cathode ray tubes to adjust the trajectory of the electron beam.
Ш Before the discovery of the law of conservation of energy, there were many attempts to use magnets to build a “perpetual motion machine”. People were attracted by the seemingly inexhaustible energy of the magnetic field of permanent magnets, which have been known for a very long time. But the working model was never built.

Meals at school should be well organized. The student must be provided with lunch and a hot breakfast in the canteen. The interval between the first and second meals should not exceed four hours. Most the best option The child should have breakfast at home, but at school he eats a second breakfast

Children's aggression at school and difficulties in the learning process
A certain relationship has been established between children's aggression and difficulties in the learning process. Every student wants to have many friends at school, have good academic performance and good grades. When a child fails to do this, he does aggressive things. Every behavior is aimed at something and has a meaning.

Advice from psychologists to parents
In any Olympiads and all kinds of competitions, a child, first of all, expresses himself and realizes himself. Parents should definitely support their child if he is passionate about intellectual competitions. It is important for a child to recognize himself as part of a society of intellectuals, in which competitive moods reign, and the child compares his achievements

A child refuses to eat in the school cafeteria
A picky child may not like school food. Often, this is the most common reason for a schoolchild to refuse to eat. It all happens because the menu at school does not take into account the taste needs of each individual child. At school, no one will exclude any product from the diet of an individual child in order to

How do parents feel about school?
In order to understand how parents feel about school, it is important to first characterize modern parents, whose age category is very diverse. Despite this, most of them are parents who belong to the generation of the nineties, who are different hard time for the entire population.

School uniform
The first school gatherings remain forever in the memory of each of us. Parents begin purchasing all the necessary office supplies starting in August. The main school attribute is the student uniform. The outfit must be carefully selected so that the first grader feels confident. Introduction school uniform is justified by many reasons.

Dear schoolchildren and students!

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Application of magnets

Date added: March 2006

It will be useful to provide a few definitions and explanations at the very beginning of the work. If, in some place, a force acts on moving bodies with a charge that does not act on stationary or chargeless bodies, then they say that a magnetic field is present in this place - one of the forms of the more general electromagnetic field.

It should be noted that different materials react differently to an external magnetic field.

There are materials that weaken the effect of an external field within themselves - paramagnetic materials and those that strengthen the external field within themselves - diamagnetic materials. There are materials with a huge ability (thousands of times) to enhance the external field inside themselves - iron, cobalt, nickel, gadolinium, alloys and compounds of these metals, they are called ferromagnets.

Among ferromagnetic materials, there are materials that, after being exposed to a sufficiently strong external magnetic field, themselves become magnets - these are hard magnetic materials. There are materials that concentrate an external magnetic field and, while it is active, behave like magnets; but if the external field disappears they do not become magnets - these are soft magnetic materials

INTRODUCTION

We are accustomed to the magnet and treat it a little condescendingly as an outdated attribute of school physics lessons, sometimes not even suspecting how many magnets there are around us. There are dozens of magnets in our apartments: in electric shavers, speakers, tape recorders, in watches, in jars of nails, finally. We ourselves are also magnets: the biocurrents flowing in us give rise to a bizarre pattern of magnetic lines of force around us. The earth we live on is a giant blue magnet. The Sun is a yellow plasma ball, an even more grandiose magnet. Galaxies and nebulae, barely visible through telescopes, are magnets of incomprehensible size. Thermonuclear fusion, magnetodynamic generation of electricity, acceleration of charged particles in synchrotrons, recovery of sunken ships - all these are areas that require enormous magnets of unprecedented size. The problem of creating strong, super-strong, ultra-strong and even stronger magnetic fields has become one of the main ones in modern physics and technology.

The magnet has been known to man since time immemorial. Mentions of magnets and their properties have reached us in the works of Thales of Miletus (approx. 600 BC) and Plato (427–347 BC). The word “magnet” itself arose due to the fact that natural magnets were discovered by the Greeks in Magnesia (Thessaly).

Artificial magnets are man-made magnets based on various ferromagnets. So-called “powder” magnets (made of iron, cobalt and some other additives) can hold a load of more than 5,000 times their own weight.

There are two different types of artificial magnets:

Some are so-called permanent magnets, made from “hard magnetic” materials. Their magnetic properties are not related to the use of external sources or currents.

Another type includes the so-called electromagnets with a core made of “soft magnetic” iron. The magnetic fields they create are mainly due to the fact that an electric current passes through the winding wire surrounding the core. In 1600, the book of the royal physician W. Gilbert “On the Magnet, Magnetic Bodies and the Great Magnet - the Earth” was published in London. This work was the first attempt known to us to study magnetic phenomena from a scientific perspective. This work contains the then available information about electricity and magnetism, as well as the results of the author’s own experiments.

Of everything that a person encounters, he first of all strives to derive practical benefit. The magnet did not escape this fate either.

In my work I will try to trace how magnets are used by humans not for war, but for peaceful purposes, including the use of magnets in biology, medicine, and in everyday life.

COMPASS, a device for determining horizontal directions on the ground. Used to determine the direction in which a ship, aircraft, or ground vehicle is moving; the direction in which the pedestrian is walking; directions to some object or landmark. Compasses are divided into two main classes: magnetic compasses of the pointer type, which are used by topographers and tourists, and non-magnetic ones, such as the gyrocompass and radio compass.

By the 11th century. refers to the message of the Chinese Shen Kua and Chu Yu about the manufacture of compasses from natural magnets and their use in navigation. If

If a long needle made of a natural magnet is balanced on an axis that allows it to rotate freely in a horizontal plane, it always faces one end to the north and the other to the south. By marking the north-pointing end, you can use such a compass to determine directions.

Magnetic effects were concentrated at the ends of such a needle, and therefore they were called poles (north and south, respectively).

In 1820, G. Oersted (1777–1851) discovered that a current-carrying conductor acts on a magnetic needle, turning it. Just a week later, Ampere showed that two parallel conductors with current in the same direction are attracted to each other. Later, he suggested that all magnetic phenomena are caused by currents, and the magnetic properties of permanent magnets are associated with currents constantly circulating inside these magnets. This assumption is fully consistent with modern ideas.

Electric machine generators and electric motors are rotational machines that convert either mechanical energy into electrical energy (generators) or electrical energy into mechanical energy (engines). The operation of generators is based on the principle of electromagnetic induction: an electromotive force (EMF) is induced in a wire moving in a magnetic field. The operation of electric motors is based on the fact that a force acts on a current-carrying wire placed in a transverse magnetic field.

Magnetoelectric devices. Such devices use the force of interaction between the magnetic field and the current in the turns of the winding of the moving part, which tends to turn the latter. Induction electricity meters. An induction meter is nothing more than a low-power AC electric motor with two windings—current and voltage windings. A conductive disk placed between the windings rotates under the influence of a torque proportional to the power consumed. This torque is balanced by currents induced in the disk by a permanent magnet, so that the rotation speed of the disk is proportional to the power consumption.

Electric wristwatches are powered by a miniature battery. They require far fewer parts to operate than mechanical watches; Thus, the circuit of a typical electric portable watch includes two magnets, two inductors and a transistor. Lock - mechanical, electrical or electronic device, limiting the possibility of unauthorized use of something. The lock can be activated by a device (key) in the possession of a certain person, information (digital or letter code), entered by that person, or any individual characteristics(for example, the pattern of the retina) of this face. A lock usually temporarily connects two assemblies or two parts together in one device. Most often, locks are mechanical, but electromagnetic locks are increasingly used.

Magnetic locks. Some models of cylinder locks use magnetic elements. The lock and key are equipped with matching code sets of permanent magnets. When the correct key is inserted into the keyhole, it attracts and positions the internal magnetic elements of the lock, allowing the lock to open.

Dynamometer - a mechanical or electrical device for measuring the traction force or torque of a machine, machine tool or engine.

Brake dynamometers come in a variety of designs; These include, for example, the Prony brake, hydraulic and electromagnetic brakes.

An electromagnetic dynamometer can be made in the form of a miniature device suitable for measuring the characteristics of small-sized engines.

The range of manufactured devices is wide and varied: switchboard devices for direct and alternating current (magnetoelectric, magnetoelectric with rectifier and electromagnetic systems), combined devices, ampere-voltmeters, for diagnosing and adjusting electrical equipment of vehicles, measuring the temperature of flat surfaces, instruments for equipping school classrooms, testers and meters of various electrical parameters

Production of abrasives - small, hard, sharp particles used in free or bound form for mechanical processing (including shaping, roughing, grinding, polishing) of various materials and products made from them (from large steel plates to plywood sheets, optical glasses and computer chips). Abrasives can be natural or artificial. The action of abrasives is reduced to removing part of the material from the surface being treated. During the production of artificial abrasives, the ferrosilicon present in the mixture settles to the bottom of the furnace, but small amounts are embedded in the abrasive and later removed by a magnet.

The magnetic properties of matter are widely used in science and technology as a means of studying the structure of various bodies. This is how science arose:

Magnetochemistry (magnetochemistry) is a branch of physical chemistry that studies the relationship between the magnetic and chemical properties of substances; In addition, magnetochemistry studies the influence of magnetic fields on chemical processes. Magnetochemistry is based on modern physics of magnetic phenomena. Studying the relationship between magnetic and chemical properties makes it possible to clarify the features of the chemical structure of a substance.

Magnetic flaw detection, a method of searching for defects based on the study of magnetic field distortions that occur at defects in products made of ferromagnetic materials.

Microwave technology

Ultra-high frequency range (UHF) - frequency range of electromagnetic radiation (100-300,000 million hertz), located in the spectrum between ultra-high television frequencies and frequencies of the far infrared region

Connection. Microwave radio waves are widely used in communications technology. In addition to various military radio systems, there are numerous commercial microwave communication lines in all countries of the world. Since such radio waves do not follow the curvature earth's surface, and propagate in a straight line, these communication lines typically consist of relay stations installed on hilltops or radio towers at intervals of about 50 km.

Heat treatment food products. Microwave radiation is used for heat treatment of food products at home and in the food industry. The energy generated by high-power vacuum tubes can be concentrated into a small volume for highly efficient thermal processing of products in the so-called. microwave or microwave ovens, characterized by cleanliness, noiselessness and compactness. Such devices are used in aircraft galleys, in railway dining cars and vending machines, where required quick preparation products and cooking. The industry also produces microwave ovens for household use. Rapid progress in the field of microwave technology is largely associated with the invention of special electrovacuum devices—magnetron and klystron—capable of generating large quantities Microwave energy. Generator based on a conventional vacuum triode, used on low frequencies, in the microwave range it turns out to be very ineffective.

Magnetron. The magnetron, invented in Great Britain before the Second World War, does not have these disadvantages, since it is based on a completely different approach to the generation of microwave radiation - the principle of a volumetric resonator

The magnetron has several volumetric resonators located symmetrically around the cathode located in the center. The device is placed between the poles of a strong magnet.

Traveling wave lamp (TWT). Another electrovacuum device for generation and amplification electromagnetic waves Microwave range – traveling wave lamp. It consists of a thin evacuated tube inserted into a focusing magnetic coil.

Modern accelerators use numerous and varied types of technology, including powerful precision magnets.

Accelerators play an important practical role in medical therapy and diagnostics. Many hospitals around the world now have small electron linear accelerators at their disposal that generate intense X-rays used to treat tumors. To a lesser extent, cyclotrons or synchrotrons generating proton beams are used. The advantage of protons over X-ray radiation in tumor therapy is a more localized energy release. Therefore, proton therapy is especially effective in treating tumors of the brain and eyes, where damage to surrounding healthy tissue should be as minimal as possible.

Representatives of various sciences take magnetic fields into account in their research. A physicist measures the magnetic fields of atoms and elementary particles, an astronomer studies the role of cosmic fields in the process of the formation of new stars, a geologist uses anomalies in the Earth’s magnetic field to find deposits of magnetic ores, and recently biology has also been actively involved in the study and use of magnets.

Biological science of the first half of the 20th century confidently described vital functions without taking into account the existence of any magnetic fields. Moreover, some biologists considered it necessary to emphasize that even a strong artificial magnetic field has no effect on biological objects.

The encyclopedias said nothing about the influence of magnetic fields on biological processes. Every year, isolated positive considerations about one or another biological effect of magnetic fields appeared in the scientific literature around the world. However, this weak trickle could not melt the iceberg of mistrust even in the formulation of the problem itself... And suddenly the trickle turned into a stormy stream. The avalanche of magnetobiological publications, as if falling from some peak, has been steadily increasing since the early 60s and drowning out skeptical statements.

From the alchemists of the 16th century to the present day, the biological effect of the magnet has found admirers and critics many times. Repeatedly over the course of several centuries, there have been surges and declines in interest in the healing effects of magnets. With its help they tried to treat (and not without success) nervous diseases, toothache, insomnia, pain in the liver and stomach - hundreds of diseases.

For medicinal purposes, magnets began to be used, probably, earlier than for determining the cardinal directions.

As a local external remedy and as an amulet, the magnet enjoyed great success among the Chinese, Indians, Egyptians, and Arabs. GREEKS, Romans, etc. The philosopher Aristotle and the historian Pliny mentioned its medicinal properties in their works.

In the second half of the 20th century, magnetic bracelets became widespread, having a beneficial effect on patients with blood pressure disorders (hypertension and hypotension).

In addition to permanent magnets, electromagnets are also used. They are also used for a wide range of problems in science, technology, electronics, medicine (nervous diseases, vascular diseases of the extremities, cardiovascular diseases, cancer).

Most of all, scientists are inclined to think that magnetic fields increase the body's resistance.

There are electromagnetic blood velocity meters, miniature capsules that, using external magnetic fields, can be moved through blood vessels to expand them, take samples at certain parts of the path, or, conversely, locally remove various medications from the capsules.

A magnetic method for removing metal particles from the eye is widely used.

Most of us are familiar with the study of heart function using electrical sensors—an electrocardiogram. Electrical impulses generated by the heart create a magnetic field of the heart, which in max values is 10-6 of the strength of the Earth's magnetic field. The value of magnetocardiography is that it allows one to obtain information about the electrically “silent” areas of the heart.

An important link uniting magnetobiological problems is the reaction of the nervous system to magnetic fields. It is the brain that first reacts to any changes in the external environment. It is the study of its reactions that will be the key to solving many problems in magnetobiology.

The simplest conclusion that can be drawn from the above is that there is no area of applied human activity where magnets are not used.

Used literature:
TSB, second edition, Moscow, 1957.

Kholodov Yu. A. “Man in the Magnetic Web”, “Knowledge”, Moscow, 1972. Materials from the Internet encyclopedia

Putilov K. A. “Physics Course”, “Fizmatgiz”, Moscow, 1964.

Repulsive properties of magnets and their use in technology

Magnets and magnetic properties of matter.

The simplest manifestations of magnetism have been known for a very long time, and are familiar to most of us. There are two different types of magnets. Some are so-called permanent magnets, made from “hard magnetic” materials. Another type includes the so-called electromagnets with a core made of “soft magnetic” iron.

Most likely the word " magnet" comes from the name ancient city Magnesia in Asia Minor, where large deposits of this mineral were located

Magnetic poles and magnetic field.

If a bar of non-magnetized iron is brought close to one of the poles of a magnet, the latter will become temporarily magnetized. In this case, the pole of the magnetized bar closest to the pole of the magnet will be opposite in name, and the far one will have the same name.

Using torsion balances, the scientist Coulomb studied the interaction of two long and thin magnets. Coulomb showed that each pole can be characterized by a certain "amount of magnetism", or "magnetic charge", and the law of interaction of magnetic poles is the same as the law of interaction electric charges: two like poles repel each other, and two unlike poles attract each other with a force that is directly proportional to " magnetic charges", concentrated at these poles, and is inversely proportional to the square of the distance between them.

Application of magnets

There are countless examples of the use of magnetic materials. Permanent magnets are very important part many devices used in our everyday life. They can be found in the pickup head, loudspeaker, electric guitar, car electric generator, small motors of tape recorders, radio microphones, electric meters and other devices. They even make “magnetic jaws,” that is, highly magnetized steel jaws that repel each other and, as a result, do not require fastenings.

Magnets are widely used in modern science. Magnetic materials needed for working in microwave ranges, for magnetic recording and playback, and for creating magnetic storage devices. Magnetostrictive transducers make it possible to determine the depth of the sea. It is difficult to do without magnetometers with highly sensitive magnetic elements if you need to measure negligibly weak magnetic fields, no matter how sophisticatedly distributed in space.

And there have been cases when they fought with magnets when they turned out to be harmful. This is the history of the times of the Great Patriotic War illustrates the responsible work of magnetism specialists in those harsh years... Let's take, for example, the magnetization of a ship's hull. Such “spontaneous” magnetization is not at all harmless: not only do the ship’s compasses begin to “lie,” mistaking the field of the ship itself for the field of the Earth and incorrectly indicating the direction, floating magnet ships can attract iron objects. If such objects are associated with mines, the result of attraction is obvious. That’s why scientists had to intervene in Nature’s tricks and specifically demagnetize ships so that they would forget how to react to magnetic mines.

Magnets are mainly used in electrical engineering, radio engineering, instrument making, automation and telemechanics.

Electric machine generators and electric motors - rotational machines that convert either mechanical energy into electrical energy (generators) or electrical energy into mechanical energy (engines). The operation of generators is based on the principle of electromagnetic induction: an electromotive force (EMF) is induced in a wire moving in a magnetic field. The operation of electric motors is based on the fact that a force acts on a current-carrying wire placed in a transverse magnetic field.

Electromagnetic dynamometer can be made in the form of a miniature device suitable for measuring the characteristics of small-sized engines.

The magnetic properties of matter are widely used in science and technology as a means of studying the structure of various bodies. This is how they arose science:

Magnetochemistry(magnetochemistry) - a branch of physical chemistry that studies the relationship between the magnetic and chemical properties of substances; In addition, magnetochemistry studies the influence of magnetic fields on chemical processes. Magnetochemistry is based on modern physics of magnetic phenomena. Studying the relationship between magnetic and chemical properties makes it possible to clarify the features of the chemical structure of a substance.

Microwave technology

Connection. Microwave radio waves are widely used in communications technology. In addition to various military radio systems, there are numerous commercial microwave communication lines in all countries of the world. Since such radio waves do not follow the curvature of the earth's surface but travel in a straight line, these communication links typically consist of relay stations installed on hilltops or radio towers at intervals of about 50 km.

Heat treatment of food products. Microwave radiation is used for heat treatment of food products at home and in the food industry. The energy generated by high-power vacuum tubes can be concentrated into a small volume for highly efficient thermal processing of products in the so-called. microwave or microwave ovens, characterized by cleanliness, noiselessness and compactness. Such devices are used in aircraft galleys, railway dining cars and vending machines, where quick food preparation and cooking are required. The industry also produces microwave ovens for household use.

With the help of a magnet they tried to treat (and not without success) nervous diseases, toothache, insomnia, pain in the liver and stomach - hundreds of diseases.

In the second half of the 20th century, magnetic bracelets became widespread, having a beneficial effect on patients with blood pressure disorders (hypertension and hypotension).

One " researcher" - shoemaker Spence from the Scottish town of Linlithgow, who lived on turn of the XVIII and 19th centuries, claimed to have discovered a certain black substance that neutralizes the attractive and repulsive forces of a magnet. According to him, with the help of this mysterious substance and two permanent magnets, he allegedly could easily maintain the continuous movement of two perpetuum mobiles of his own making. We present this information today as a typical example of naive ideas and simple-minded beliefs, which science had difficulty getting rid of even in later times. One might assume that Spence's contemporaries would not have even a shadow of doubt about the meaninglessness of the ambitious shoemaker's fantasies. However, one Scottish physicist felt it necessary to mention this case in his letter published in the journal Annals of Chemistry" in 1818, where he writes:

"... Mr. Playfair and Captain Cater examined both of these machines and expressed satisfaction that the problem of perpetual motion had finally been solved."

Thus, it turns out that the properties of magnets are widely used in many things, and are quite useful for all of humanity as a whole.