The use of magnets. The use of permanent magnets in electrical engineering and power industry

At the very beginning of the work, it will be useful to give a few definitions and explanations.

If, in some place, moving bodies with a charge are affected by a force that does not act on stationary or uncharged bodies, then they say that there is a a magnetic field one of the forms of the more generalelectromagnetic field.

There are bodies that can create a magnetic field around them (and such a body is also affected by the force of the magnetic field), they are said to be magnetized and have a magnetic moment, which determines the property of the body 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 an external field inside themselves paramagnets and reinforcing the external field within themselves diamagnets.

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 calledferromagnets.

There are materials among ferromagnets that, after exposure to a sufficiently strong external magnetic field, become magnets themselves thishard magnetic materials.

There are materials that concentrate an external magnetic field in themselves and, while it acts, behave like magnets; but if the external field disappears they do not become magnets thissoft 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We are accustomed to the magnet and treat it a little condescendingly as an outdated attribute of school physics lessons, sometimes not even suspecting how many magnets there are around us.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 around us to a bizarre pattern of magnetic lines of force. The earth we live on is a giant blue magnet. Sun yellow plasma ball even grander magnet. Galaxies and nebulae, barely distinguishable by telescopes, are magnets incomprehensible in size. Thermonuclear fusion, magnetodynamic power generation, acceleration of charged particles in synchrotrons, recovery of sunken ships - all these are areas where grandiose magnets, never seen before in size, are required. The problem of creating strong, superstrong, ultrastrong and even stronger magnetic fields has become one of the main problems in modern physics and technology.

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

about magnets and their properties in the worksThales of Miletus (approx. 600 BC) and Plato (427347 BC). The very word "magnet" arose due to the fact that natural magnets were discovered by the Greeks in Magnesia (Thessaly).

Natural (or natural) magnets are found in nature in the form of deposits of magnetic ores. The University of Tartu has the largest known natural magnet. Its mass is 13 kg, and it is able to lift a load of 40 kg.

Artificial magnets are magnets created by man on the basis of variousferromagnets. So-called "powder" magnets (made of iron, cobalt and some other additives) can hold a load of more than 5000 times their own weight.

FROM There are two different types of artificial magnets:

Some the so-calledpermanent magnetsmade 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 from " soft magnetic» gland. The magnetic fields created by them are mainly due to the fact that an electric current passes through the wire of the winding covering the core.

In 1600, a book by the royal physician W. Gilbert “On the magnet, magnetic bodies and the large magnet - the Earth” was published in London. This work was the first attempt known to us to study 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.

From everything that a person encounters, he first of all seeks to derive practical benefit. Did not pass this fate and the magnet

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

USE OF MAGNETS.

COMPASS, a device for determining horizontal directions on the ground. It is used to determine the direction in which the sea, aircraft, 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 such as arrows, which are used by topographers and tourists, and non-magnetic, such as a gyrocompass and a 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 a

Since a long needle made of a natural magnet is balanced on an axis that allows it to freely rotate in a horizontal plane, it always faces north at one end and south at the other. By marking the end pointing north, 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).

The main application of the magnet is in electrical engineering, radio engineering, instrumentation, automation and telemechanics. Here, ferromagnetic materials are used to manufacture magnetic circuits, relays, etc.

In 1820, G. Oersted (17771851) discovered that a conductor with current acts on a magnetic needle, turning it. Literally a week later, Ampere showed that two parallel conductors with current in the same direction attract each other. Later, he suggested that all magnetic phenomena are due to 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 -rotary machines that convert either mechanical energy into electrical energy (generators) or electrical energy into mechanical energy (motors). 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 action 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 of the magnetic field with the current in the turns of the winding of the moving part, tending to rotate the latter

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

Electric wrist watchpowered by a miniature battery. They require far fewer parts to operate than mechanical watches; for example, a typical electric portable clock has two magnets, two inductors, and a transistor.

Lock - a mechanical, electrical, or electronic device that restricts the unauthorized use of something. The lock can be actuated by a device (key) held by a certain person, information (digital or alphabetic code) entered by this person, or some individual characteristic (for example, retinal pattern) of this person. The lock usually temporarily connects two nodes or two parts to each other in one device. Most often, locks are mechanical, but electromagnetic locks are increasingly being used.

Magnetic locks. Cylinder locks of some models use magnetic elements. The lock and the key are equipped with counter coded sets of permanent magnets. When the correct key is inserted into the keyhole, it attracts and sets the internal magnetic elements of the lock into position, which allows the lock to be opened.

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

Brake dynamometersthere are a variety of designs; these include, for example, the Prony brake, hydraulic and electromagnetic brakes.

Electromagnetic dynamometercan be made in the form of a miniature device suitable for measuring the characteristics of small engines.

Galvanometer sensitive device for measuring weak currents. The galvanometer uses the torque generated by the interaction of a horseshoe-shaped permanent magnet with a small current-carrying coil (weak electromagnet) suspended in the gap between the poles of the magnet. The torque, and hence 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 instrument is almost linear with small deflections of the coil. Devices based on it are the most common type of devices.

The range of devices produced is wide and varied: switchboard devices for direct and alternating current (magnetoelectric, magnetoelectric with a rectifier and electromagnetic systems), combined devices, ampere-voltmeters, for diagnosing and adjusting electrical equipment of cars, measuring the temperature of flat surfaces, devices 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, peeling, grinding, polishing) of various materials and products from them (from large steel plates to plywood sheets, optical glasses and computer chips). Abrasives are either natural or artificial. The action of abrasives is to remove part of the material from the treated surface.During the production of artificial abrasives, the ferrosilicon present in the mixture settles to the bottom of the furnace, but small amounts of it 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. So arose science:

Magnetokh and mia (magnetochemistry) - a section of physical chemistry that studies the relationship between the magnetic and chemical properties of substances; in addition, magnetochemistry investigates the influence of magnetic fields on chemical processes. magnetochemistry is based on modern physics of magnetic phenomena. The study of the relationship between magnetic and chemical properties makes it possible to elucidate the features of the chemical structure of a substance.

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

. Microwave technology

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

Connection. Microwave radio waves are widely used in communications technology. In addition to various military radio systems, there are numerous commercial microwave links in all countries of the world. Since such radio waves do not follow the curvature of the earth's surface, but propagate in a straight line, these communication links typically consist of relay stations installed on hilltops or on 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 powerful vacuum tubes can be concentrated in a small volume for highly efficient cooking 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 fast food preparation and cooking is required. The industry also produces household microwave ovens.

The rapid progress in the field of microwave technology is largely associated with the invention of special electrovacuum devices - the magnetron and the klystron, capable of generating large amounts of microwave energy. An oscillator based on a conventional vacuum triode, used at low frequencies, turns out to be very inefficient in the microwave range.

Magnetron. In the magnetron, invented in Great Britain before the Second World War, these shortcomings are absent, since a completely different approach to the generation of microwave radiation is taken as a basis the principle of a cavity resonator

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

Traveling wave lamp (TWT).Another electrovacuum device for generating and amplifying electromagnetic waves in the microwave range is a traveling wave lamp. It is a thin evacuated tube inserted into a focusing magnetic coil.

particle accelerator, an installation in which, with the help of electric and magnetic fields, directed beams of electrons, protons, ions and other charged particles with an energy much higher than thermal energy are obtained.

Numerous and diverse types of technology are used in modern accelerators, incl. powerful precision magnets.

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

Representatives of various sciences take into account magnetic fields 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 the anomalies of 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 sciencefirst half XX century confidently described vital functions, not at all considering the existence of any magnetic fields. Moreover, some biologists considered it necessary to emphasize that even a strong artificial magnetic field does not have any effect on biological objects.

In encyclopedias, nothing was said about the influence of magnetic fields on biological processes. In the scientific literature of the whole world, single positive considerations about one or another biological effect of magnetic fields appeared every year. However, this weak brook could not melt the iceberg of distrust even in the formulation of the problem itself... And suddenly the brook turned into a turbulent stream. The avalanche of magnetobiological publications, as if breaking off from some peak, has been constantly increasing since the beginning of the 1960s and drowning out skeptical statements.

From the Alchemists XVI century and up to the present day, the biological effect of the magnet has many times found admirers and critics. Repeatedly over the course of several centuries, surges and recessions of interest in the therapeutic effect of the magnet were observed. 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, the magnet began to be used, probably earlier than for determining the cardinal points.

As a local external remedy and as an amulet, the magnet was very popular with the Chinese, Hindus, Egyptians, and Arabs. GREEKS, Romans, etc. Its healing properties are mentioned in their writings by the philosopher Aristotle and the historian Pliny.

In the second half XX century, magnetic bracelets have been widely distributed, which have a beneficial effect on patients with impaired blood pressure (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, cancers).

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

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

The magnetic method of removing metal particles from the eye is widely used.

Most of us are familiar with the study of the work of the heart using electrical sensors electrocardiogram. The electrical impulses generated by the heart create a magnetic field in the heart, which max values is 10-6 strength of the earth's magnetic field. The value of magnetocardiography is that it provides 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 demand more verified biological facts from biologists. It is obvious that close cooperation of various specialists will be successful.

An important link uniting magnetobiological problems is the response 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 of 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.

References:

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", "Physmatgiz", Moscow, 1964.

Ø Magnetic media: VHS cassettes contain reels of magnetic tape. Video and audio information is encoded on the magnetic coating on the tape. Also in computer floppy disks and hard disks, data is recorded on a thin magnetic coating. However, storage media are not strictly magnets, as they do not attract objects. Magnets in hard drives are used in the drive and positioning motors.
• 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.
• Conventional TVs and computer monitors: TVs and computer monitors containing a cathode ray tube use an electromagnet to control the electron beam and form an image on the screen. Plasma panels and LCD monitors use other technologies.
• Loudspeakers and microphones: Most loudspeakers use a permanent magnet and a current coil to convert electrical energy (signal) into mechanical energy (motion that creates sound). The winding is wound on a coil, attached to the diffuser, and an alternating current flows through it, which interacts with the field of a permanent magnet.
Ш Another example of the use of magnets in sound engineering is in the pickup head of an electrophone and in cassette recorders as an economical erasing head.
Ш Magnetic separator of heavy minerals
• Electric motors and generators: Some electric motors (like 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 magnetically coupled.
SH Magnets are used in polarized relays. Such devices remember their state at the time of power off.
Ø Compasses: A compass (or nautical compass) is a magnetized pointer that is free to rotate and orients itself to the direction of a magnetic field, most commonly the earth's magnetic field.
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
SH 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 may have a magnetic clasp, or may be made entirely from a series of linked magnets and black beads.
• Magnets can pick up magnetic objects (iron nails, staples, tacks, paper clips) that are either too small, hard to reach, or too thin to hold 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 the so-called "Magnetic Test", in which the car body is examined with a magnet to identify areas repaired using fiberglass or plastic putty.
Ш Maglev: a train on a magnetic suspension, 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 running surface, friction is eliminated and the only braking force is the aerodynamic drag force.
Ш Magnets are used in fixing furniture doors.
Ш If the magnets are placed in sponges, then these sponges can be used to wash thin sheet non-magnetic materials from both sides at once, and one side may be difficult to reach. It can be, for example, the glass of an aquarium or a balcony.
Ш Magnets are used to transmit torque "through" the wall, which can be, for example, a sealed container of an electric motor. So the toy of the GDR "Submarine" was arranged.
Ш Magnets together with a reed switch are used in special position sensors. For example, in refrigerator door sensors and burglar alarms.
Ш Magnets together with a Hall sensor are used to determine the angular position or angular velocity of the shaft.
Ш Magnets are used in spark gaps to speed up arc quenching.
Ш Magnets are used in non-destructive testing by magnetic particle method (MPC)
Ш Magnets are used to deflect beams of radioactive and ionizing radiation, for example, when observing in cameras.
Ш Magnets are used in indicating devices with a deviating 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 the deflecting system of cathode-ray tubes for adjusting the trajectory of the electron beam.
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 a permanent magnet, which have been known for a very long time. But the working layout was never built.

One of the most amazing natural phenomena is the manifestation of magnetism in some materials. Permanent magnets have been known since ancient times. Before the great discoveries in the field of electricity, permanent magnets were actively used by doctors of different peoples in medicine. They got to people from the bowels of the earth in the form of pieces of magnetic iron ore. Over time, people learned to create artificial magnets by placing iron alloy products next to natural sources of a magnetic field.

The nature of magnetism

Demonstration of the properties of a magnet in attracting metal objects to itself in people raises the question: what are permanent magnets? What is the nature of such a phenomenon as the appearance of a thrust of metal objects towards magnetite?

The first explanation of the nature of magnetism was given in his hypothesis by the great scientist - Ampère. In any matter, electric currents of varying degrees of strength flow. Otherwise they are called Ampere currents. Electrons, rotating around their own axis, also revolve around the nucleus of the atom. Due to this, elementary magnetic fields arise, which, interacting with each other, form the general field of matter.

In potential magnetites, in the absence of external influence, the fields of the elements of the atomic lattice are randomly oriented. An external magnetic field “builds” the microfields of the material structure in a strictly defined direction. The potentials of the opposite ends of the magnetite repel each other. If we approach the same poles of two strip PMs, then the human hands will feel resistance to movement. Different poles will tend to each other.

When steel or an iron alloy is placed in an external magnetic field, the internal fields of the metal are strictly oriented in one direction. As a result, the material acquires the properties of a permanent magnet (PM).

How to see the magnetic field

To visually feel the structure of the magnetic field, it is enough to conduct a simple experiment. To do this, take two magnets and small metal chips.

Important! In everyday life, permanent magnets are found in two forms: in the form of a straight strip and a horseshoe.

Having covered the strip PM with a sheet of paper, iron filings are poured onto it. The particles instantly line up along the magnetic field lines, which gives a visual representation of this phenomenon.

Types of magnets

Permanent magnets are divided into 2 types:

natural;
artificial.

Natural

In nature, a natural permanent magnet is a fossil in the form of a fragment of iron ore. Magnetic rock (magnetite) in each nation has its own name. But in each name there is such a thing as “loving”, “attractive metal”. The name Magnitogorsk means the location of the city next to the mountain deposits of natural magnetite. For many decades, active mining of magnetic ore was carried out here. Nothing remains of Magnetic Mountain today. It was the development and extraction of natural magnetite.

Until the proper level of scientific and technological progress was achieved by mankind, natural permanent magnets served for various fun and tricks.

artificial

Artificial PMs are obtained by inducing an external magnetic field on various metals and their alloys. It was noticed that some materials retain the acquired field for a long time - they are called solid magnets. Materials that quickly lose the properties of permanent magnets are called soft magnets.

In the conditions of factory production, complex metal alloys are used. The structure of the alloy "magnico" includes iron, nickel and cobalt. Alnico alloy contains aluminum instead of iron.

Products from these alloys interact with powerful electromagnetic fields. As a result, quite powerful PMs are obtained.

Applications of permanent magnets

PM is of no small importance in various fields of human activity. Depending on the scope of application, PM have different characteristics. Recently, the actively used main magnetic alloyNdFeBconsists of the following chemical elements:

"Nd" - niodium,
"Fe" - iron,
"B" - boron.

Areas where permanent magnets are used:

Ecology;
electroplating;
The medicine;
Transport;
Computer techologies;
Household appliances;
Electrical engineering.

Ecology

Various industrial waste treatment systems have been developed and are in operation. Magnetic systems purify liquids during the production of ammonia, methanol and other substances. Magnetic traps “select” all iron-containing particles from the flow.

Ring-shaped PMs are installed inside gas ducts, which rid gaseous exhausts of ferromagnetic inclusions.

Separator magnetic traps actively select metal-containing waste on conveyor lines for the processing of man-made waste.

Electroplating

Galvanic production is based on the movement of charged metal ions to opposite poles of DC electrodes. PMs play the role of product holders in the galvanic pool. In industrial installations with galvanic processes, only NdFeB magnets are installed.

The medicine

Recently, manufacturers of medical equipment have widely advertised devices and devices based on permanent magnets. A constant intense field is provided by the characteristic of the NdFeB alloy.

The property of permanent magnets is used to normalize the circulatory system, extinguish inflammatory processes, restore cartilage tissue, and so on.

Transport

Transport systems in production are equipped with installations with PM. During the conveyor movement of raw materials, magnets remove unnecessary metal inclusions from the array. With the help of magnets, various products are directed in different planes.

Note! Permanent magnets are used to separate such materials where the presence of people can be detrimental to their health.

Automobile transport is equipped with a mass of instruments, components and devices, where PM plays the main role. These are electronic ignition, automatic power windows, idle control, gasoline, diesel pumps, front panel instruments and much more.

Computer techologies

All mobile devices and devices in computer technology are equipped with magnetic elements. The list includes printers, driver engines, drive motors, and other devices.

household appliances

Basically, these are holders of small household items. Shelves with magnetic holders, curtain and curtain holders, holders for a set of kitchen knives and a host of other household appliances.

electrical engineering

Electrical engineering, built on PM, concerns such areas as radio engineering devices, generators and electric motors.

Radio engineering

PM is used to increase the compactness of radio engineering devices, to ensure the autonomy of devices.

Generators

Generators on PM solve the problem of moving contacts - rings with brushes. In traditional devices for industrial use, there are acute issues related to complex maintenance of equipment, rapid wear of parts, and significant loss of energy in the excitation circuits.

The only obstacle to the creation of such generators is the problem of mounting the PM on a rotating rotor. Recently, magnets are placed in the longitudinal grooves of the rotor, filling them with fusible material.

Electric motors

In household appliances and in some industrial equipment, permanent magnet synchronous electric motors have become widespread - these are DC brushless motors.

As in the generators described above, the PM is mounted on rotors rotating inside stators with a fixed winding. The main advantage of the electric motor is the absence of short-lived current-carrying contacts on the rotor collector.

Motors of this type are low-power devices. However, this does not in the least diminish their usefulness in the field of electrical engineering.

Additional Information. A distinctive feature of the device is the presence of a Hall sensor that regulates the speed of the rotor.

The author hopes that after reading this article, the reader will have a clear idea of what a permanent magnet is. The active introduction of permanent magnets into the sphere of human activity stimulates the invention and creation of new ferromagnetic alloys with enhanced magnetic characteristics.

Video

At the very beginning of the work, it will be useful to give a few definitions and explanations.

If, in some place, moving bodies with a charge are affected by a force that does not act on stationary or uncharged bodies, then they say that there is a a magnetic field one of the more general forms 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 inside themselves – paramagnets and reinforcing the external field within themselves – diamagnets.

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

There are materials that concentrate an external magnetic field in themselves and, while it acts, behave like magnets; but if the external field disappears, they do not become magnets - this is 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 around us to a bizarre pattern of magnetic lines of force. The earth we live on is a giant blue magnet. The sun is a yellow plasma ball - an even grander magnet. Galaxies and nebulae, barely distinguishable by telescopes, are magnets incomprehensible in size. Thermonuclear fusion, magnetodynamic power generation, the acceleration of charged particles in synchrotrons, the recovery of sunken ships - all these are areas where grandiose, never-before-seen magnets are required. The problem of creating strong, superstrong, ultrastrong and even stronger magnetic fields has become one of the main problems in modern physics and technology.

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

about magnets and their properties in the writings of Thales of Miletus (ca. 600 BC) and Plato (427–347 BC). The very word "magnet" arose due to the fact that natural magnets were discovered by the Greeks in Magnesia (Thessaly).

Artificial magnets are magnets created by man on the basis of various ferromagnets. So-called "powder" magnets (made of iron, cobalt and some other additives) can hold a load of more than 5000 times their own weight.

There are two different types of artificial magnets:

One is the 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 of " soft magnetic » iron. The magnetic fields created by them are mainly due to the fact that an electric current passes through the wire of the winding covering the core.

In my work, I will try to trace how magnets are used by people 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. It is used to determine the direction in which the sea, aircraft, 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 such as arrows, which are used by topographers and tourists, and non-magnetic, such as a gyrocompass and a 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 a

a long needle made of a natural magnet is balanced on an axis that allows it to freely rotate in a horizontal plane, it always faces north with one end and south with the other. By marking the end pointing north, 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 conductor with current acts on a magnetic needle, turning it. Literally a week later, Ampere showed that two parallel conductors with current in the same direction attract each other. Later, he suggested that all magnetic phenomena are due to 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 - rotary machines that convert either mechanical energy into electrical energy (generators) or electrical energy into mechanical energy (motors). 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 action 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 of the magnetic field with the current in the turns of the winding of the moving part, tending to rotate the latter

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

Electric wrist watch powered by a miniature battery. They require far fewer parts to operate than mechanical watches; for example, a typical electric portable clock has two magnets, two inductors, and a transistor.

Lock - a mechanical, electrical, or electronic device that restricts the unauthorized use of something. The lock can be actuated by a device (key) held by a certain person, information (digital or alphabetic code) entered by this person, or some individual characteristic (for example, retinal pattern) of this person. The lock usually temporarily connects two nodes or two parts to each other in one device. Most often, locks are mechanical, but electromagnetic locks are increasingly being used.

Magnetic locks. Cylinder locks of some models use magnetic elements. The lock and the key are equipped with counter coded sets of permanent magnets. When the correct key is inserted into the keyhole, it attracts and sets the internal magnetic elements of the lock into position, which allows the lock to be opened.

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

Brake dynamometers there are a variety of designs; these include, for example, the Prony brake, hydraulic and electromagnetic brakes.

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

Galvanometer- a sensitive device for measuring weak currents. The galvanometer uses the torque generated by the interaction of a horseshoe-shaped permanent magnet with a small current-carrying coil (weak electromagnet) suspended in the gap between the poles of the magnet. The torque, and hence 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 instrument is almost linear with small deflections of the coil. Devices based on it are the most common type of devices.

Production abrasives - small, hard, sharp particles used in free or bound form for mechanical processing (including shaping, peeling, grinding, polishing) of various materials and products from them (from large steel plates to plywood sheets, optical glasses and computer chips). Abrasives are either natural or artificial. The action of abrasives is to remove part of the material from the treated surface. During the production of artificial abrasives, the ferrosilicon present in the mixture settles to the bottom of the furnace, but small amounts of it 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. So arose science:

magnetochemistry(magnetochemistry) - a section of physical chemistry that studies the relationship between the magnetic and chemical properties of substances; in addition, magnetochemistry investigates the influence of magnetic fields on chemical processes. magnetochemistry is based on modern physics of magnetic phenomena. The study of the relationship between magnetic and chemical properties makes it possible to elucidate the features of the chemical structure of a substance.

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

. Microwave technology

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

Connection. Microwave radio waves are widely used in communications technology. In addition to various military radio systems, there are numerous commercial microwave links in all countries of the world. Since such radio waves do not follow the curvature of the earth's surface, but propagate in a straight line, these communication links typically consist of relay stations installed on hilltops or on 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 powerful vacuum tubes can be concentrated in a small volume for highly efficient cooking 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 fast food preparation and cooking is required. The industry also produces household microwave ovens.

Magnetron. In the magnetron, invented in Great Britain before the Second World War, these shortcomings are absent, since a completely different approach to the generation of microwave radiation is taken as the basis - the principle of a cavity resonator

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

Traveling wave lamp (TWT). Another electrovacuum device for generating and amplifying electromagnetic waves in the microwave range is a traveling wave lamp. It is a thin evacuated tube inserted into a focusing magnetic coil.

particle accelerator, an installation in which, with the help of electric and magnetic fields, directed beams of electrons, protons, ions and other charged particles with an energy much higher than thermal energy are obtained.

Numerous and diverse types of technology are used in modern accelerators, incl. powerful precision magnets.

biological science of the first half of the 20th century confidently described vital functions, not at all taking into account the existence of any magnetic fields. Moreover, some biologists considered it necessary to emphasize that even a strong artificial magnetic field does not have any effect on biological objects.

From the alchemists of the 16th century to the present day, the biological action of the magnet has found admirers and critics many times. Repeatedly over the course of several centuries, surges and recessions of interest in the therapeutic effect of the magnet were observed. 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, the magnet began to be used, probably earlier than for determining the cardinal points.

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).

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

The magnetic method of removing metal particles from the eye is widely used.

Most of us are familiar with the study of the work of the heart with the help of electrical sensors - an electrocardiogram. The electrical impulses produced by the heart create a magnetic field of the heart, which in max values is 10 -6 of the Earth's magnetic field strength. The value of magnetocardiography is that it provides information about the electrically "silent" areas of the heart.

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

References:

1) TSB, second edition, Moscow, 1957

3) Materials from the Internet - encyclopedia

4) Putilov K.A. "Physics course", "Physmatgiz", Moscow, 1964.

First you need to understand what a magnet is in general. A magnet is a natural energy material that has an inexhaustible energy field and two poles, which are called north and south. Although in our time, humanity, of course, has learned to create this unusual phenomenon artificially.

Man has learned to use the power of the two poles of a magnet almost everywhere. Modern society uses a fan on a daily basis - there are special magnetic brushes in its engine, absolutely every day and until late at night they watch TV, work on a computer, and there are a fairly large number of these elements in it. Everyone in the house has a clock hanging on the wall, all sorts of beautiful little toys on the refrigerator door, speakers on all sound equipment work solely thanks to this wonderful magnet.

In industrial enterprises, workers use electric motors, welding machines. The construction uses a magnetic crane, iron separating tape. The built-in magnetic device helps to completely separate the chips and scale from the finished product. These magnetic tapes are also used in the food industry.

Another magnet is used in jewelry, and these are bracelets, chains, all kinds of pendants, rings, earrings, and even hairpins.

We need to understand that without this natural element, our existence will become much more difficult. Many objects and devices use magnets - from children's toys to quite serious things. After all, it is not in vain that in electrical engineering and physics there is a special section - electricity and magnetism. These two sciences are closely related. All objects where this element is present cannot be immediately listed.

Nowadays, more and more new inventions appear and many of them contain magnets, especially if it is related to electrical engineering. Even the world famous collider works exclusively with the help of electromagnets.

The magnet is also widely used for medical purposes - for example, for resonant scanning of human internal organs, as well as for surgical purposes. It is used for all kinds of magnetic belts, massage chairs and so on. The healing properties of a magnet are not invented - for example, in Georgia on the Black Sea there is a unique resort of Ureki, where the sand is not ordinary - yellow, but black - magnetic. Many people go there to treat many diseases, especially for children - cerebral palsy, nervous disorders, and even hypertension.

Magnets are also used in processing plants. For example, old cars are first crushed with a press, and then loaded with a magnetic loader.

There are also so-called neodymium magnets. They are used in various industries where the temperature does not exceed 80°C. These magnets are now used almost everywhere.

Magnets are now so closely integrated into our lives that without them our life will become very difficult - approximately at the level of the 18th and 19th centuries. If all the magnets were to disappear right now, we would instantly lose electricity - only such sources of it as accumulators and batteries would remain. Indeed, in the device of any current generator, the most important part is precisely the magnet. And do not think that your car will start on battery power - the starter is also an electric motor, where the most important part is the magnet. Yes, you can live without magnets, but you will have to live the way our ancestors lived 100 years or more ago ...