To explain the magnetization of bodies, Ampere suggested that circular currents (molecular currents) circulate in the molecules of the substance. Each such current has a magnetic moment and creates a magnetic field in the surrounding space. In the absence external field molecular currents are randomly oriented, as a result of which the resulting field caused by them is equal to zero. Due to the chaotic orientation of the magnetic moments of individual molecules, the total magnetic moment bodies also equal to zero. Under the influence of a field, the magnetic moments of molecules acquire a predominant orientation in one direction, as a result of which the magnet is magnetized - its total magnetic moment becomes non-zero. The magnetic fields of individual molecular currents in this case no longer compensate each other and field B appears
At the beginning of the study of magnetism to explain the properties permanent magnets Ampere put forward a bold hypothesis at that time about the existence of so-called “molecular currents”, the totality of which explains magnetic properties substances. At present, Ampere's hypothesis seems almost obvious; the physical mechanisms responsible for the magnetic properties of substances have been studied much more deeply than was possible in Ampere's time
Ampere's hypothesis. Ampere(1775-1836) put forward a hypothesis about the existence of electric currents circulating inside each molecule of a substance. In 1897 The hypothesis was confirmed by the English scientist Thomson, and in 1910. The currents were measured by the American scientist Millikan. Conclusion: the movement of electrons is circular current, but that there is a magnetic field around a conductor carrying electric current.
Magnetic field- This special kind matter, specific feature which is the action on the moving electric charge, conductors with current, bodies with a magnetic moment, with a force depending on the charge velocity vector, the direction of the current in the conductor and the direction of the magnetic moment of the body.
The history of magnetism goes back to ancient times, to ancient civilizations Asia Minor. It was on the territory of Asia Minor, in Magnesia, that they found rock, the samples of which were attracted to each other. Based on the name of the area, such samples began to be called “magnets”. Any bar or horseshoe-shaped magnet has two ends called poles; It is in this place that its magnetic properties are most pronounced. If you hang a magnet on a string, one pole will always point north. The compass is based on this principle. The north-facing pole of a freely hanging magnet is called north pole magnet (N). The opposite pole is called south pole(S).
Magnetic poles interact with each other: like poles repel, and unlike poles attract. Similar to the concept of an electric field surrounding an electric charge, the concept of a magnetic field around a magnet is introduced.
In 1820, Oersted (1777-1851) discovered that the magnetic needle located next to electrical conductor, deflects when current flows through the conductor, i.e., a magnetic field is created around the current-carrying conductor. If we take a frame with current, then the external magnetic field interacts with the magnetic field of the frame and has an orienting effect on it, i.e. there is a position of the frame at which the external magnetic field has a maximum rotating effect on it, and there is a position when the torque force is zero.
Source current (in theory electrical circuits) - an element, a two-terminal network, the current through which does not depend on the voltage at its terminals (poles). The terms current generator and ideal are also used. source current
Magnetic induction.
If the charge of a particle is q, its speed is v, and the induction magnetic field at a given point in space is equal to B, then a force equal to:
Thus, B is a vector whose magnitude and direction are such that the Lorentz force acting on a moving charge from the magnetic field is equal to:
Here alpha is the angle between the velocity vector and the magnetic induction vector. The Lorentz force vector F is perpendicular to the velocity vector and the magnetic induction vector. Its direction for the case of motion of a positively charged particle in a uniform magnetic field is determined by the left-hand rule:
"If left hand positioned so that the magnetic induction vector enters the palm, and the four extended fingers are directed in the direction of movement of the positively charged particle, then bent 90 degrees thumb will show the direction of the Lorentz force.”
Since the current in a conductor is the movement of charged particles, magnetic induction can also be defined as the ratio of the maximum mechanical moment acting from a uniform magnetic field on a frame with current to the product of the current in the frame and the area of the frame:
Magnetic induction is a fundamental characteristic of a magnetic field, like strength for an electric field. In the SI system, magnetic induction is measured in tesla (T), in GHS system- in Gauss (Gs). 1 Tesla = 10,000 Gauss. 1 T is the induction of such a uniform magnetic field in which a maximum mechanical torque of 1 N m acts on a frame with an area of 1 m2, through which a current of 1 A flows.
By the way, the induction of the Earth's magnetic field at a latitude of 50° is on average 0.00005 Tesla, and at the equator - 0.000031 Tesla. The magnetic induction vector is always directed tangentially to the magnetic field line.
A circuit placed in a uniform magnetic field is penetrated by a magnetic flux Ф, the flux of the magnetic induction vector. The magnitude of the magnetic flux Ф depends on the direction of the magnetic induction vector relative to the circuit, on its magnitude, and on the area of the circuit penetrated by the lines of magnetic induction. If vector B is perpendicular to the contour area, then magnetic flux F penetrating the contour will be maximum.
Magnetic forces.
The magnetic field that acts is called force. The force acting on the current conductor, the length of the conductor, the magnetic direction of the magnetic vector is determined by the rule of the left moving charges widely in the cyclotron-accelerator of elementary It is well known that magnetic permanent magnets. Constant substances, but all substances create a magnetic field. According to microscopic currents, Faraday's Law, the basic law of emf. induction in a conductor crosses magnetic force If a closed conductor a changing magnetic conductor in a magnetic field creating at the other end of the conductor a difference occurs only when the conductor conductor is removed from the magnetic Electromagnetic conductor when Voltage induced by the emf of which the angle of the field moves more Relative arise due to the movement of the field or both of them move at right angles less than 90 degrees, the conductor moves in parallel, the more the induced force acts with a certain force on the conductor with the current Ampere force.
FA = I B ∆l sin α.
on the conductor through which the current flows is directly proportional to the conductor, magnetic induction and the sine of the angle between the direction of the magnetic induction vector. Direction of Ampere's force to the left-hand rule. In addition, the magnetic field acts on a particle located in the magnetic field called the Lorentz force. The Lorentz force can be determined by the formula:
FL = qυ Bsin α.
The Lorentz force acts on a moving particle from the magnetic side, which is perpendicular and does not do any work. Magnetic action is widely used in modern technology, for example an accelerator elementary particles. the magnetic field is created not only electric magnets. Permanent magnets can be made by substances placed in a magnetic field, which are magnetized by the field. According to Ampere's hypothesis, these fields are generated by currents circulating inside atoms and molecules; the basic law of electromagnetism is formulated as a conductor is directly proportional to the speed with which the magnetic lines of force, i.e. rate of change magnetic conductor moves in a magnetic field or is in a magnetic field, then a electric current In this field, electrons move to one end of the conductor because there is a shortage of electrons. As a result, a potential difference arises. This potential difference moves the conductor relative to the magnetic field, free electrons are returning Electromagnetic induction takes place in two conductors moves relative to the magnetic field when the magnetic field moves relative to the voltage that occurs in the conductor is called induced voltage, or emf induced emf. determined by the magnitude of the magnetic field through which the conductor moves relative to the angle at which the conductor is located relative to the field, and the length of the conductor. The stronger the magnetic field, the greater the emf value. induction.
The faster it moves relative to the field, the more Relative motion conductor and the magnetic movement of the conductor (but not along the other itself. The maximum voltage is induced at a right angle to power lines Magnetic degrees less voltage is induced. If parallel to the lines of force, the emf. Induction voltage no longer occurs.
Magnetic properties of substances.
Every substance is magnetic, i.e. is capable of acquiring a magnetic moment (magnetization) under the influence of a magnetic field. According to the magnitude and direction of this moment, as well as the reasons that gave rise to it, all substances are divided into groups. The main ones are dia- and paramagnets.
Diamagnetic molecules do not have their own magnetic moment. It arises in them only under the influence of an external magnetic field and is directed against it. Thus, the resulting magnetic field in a diamagnetic material is less than the external field, although by a very small amount. This leads to the fact that when a diamagnetic material is placed in a non-uniform magnetic field, it tends to shift to the region where the magnetic field voltage is lower.
Molecules (or atoms) of a paramagnetic material have their own magnetic moments, which, under the influence of external fields, are oriented along the field and thereby create a resulting field that exceeds the external one. Paramagnetic substances are drawn into a magnetic field. For example, liquid oxygen is paramagnetic and is attracted to a magnet.
There are a number of substances in which quantum effects interatomic interactions lead to the appearance of specific magnetic properties.
Most interesting property- ferromagnetism. It is characteristic of a group of substances in solids crystalline state(ferromagnets), characterized by parallel orientation of the magnetic moments of atomic carriers of magnetism.
Parallel orientation of magnetic moments exists in fairly large areas of matter - domains. The total magnetic moments of individual domains are very large amount, however, the domains themselves are usually randomly oriented in the substance. When a magnetic field is applied, the orientation of the domains occurs, which leads to the appearance of a total magnetic moment in the entire volume of the ferromagnet, and, as a consequence, to its magnetization.
Naturally, ferromagnets, like paramagnets, move to the point of the field where the intensity is maximum (they are drawn into the magnetic field). Because of large size magnetic permeability, the force acting on them is much greater.
The Curie temperature range for ferromagnets is very wide: for radolinium the Curie temperature is 20 0 C, for pure iron- 1043 K. It is almost always possible to select a substance with the desired Curie temperature.
As the temperature decreases, all paramagnets, except those in which paramagnetism is due to conduction electrons, pass into either a ferromagnetic or antiferromagnetic state.
For antiferromagnets there is also a temperature at which the antiparallel spin orientation disappears. This temperature is called the antiferromagnetic Curie point or Néel point.
Some ferromagnets (erbine, diobrosine, manganese and copper alloys) have two such temperatures (upper and lower Néel points), and antiferromagnetic properties are observed only at intermediate temperatures. Above the upper point, the substance behaves as a paramagnet, and at temperatures below the lower Néel point, it becomes ferromagnetic.
Ferrimagnetism- (or uncompensated antiferromagnetism) a set of magnetic properties of substances (ferromagnets) in the solid state, caused by the presence of electron-electron exchange interaction inside the body, tending to create an antiparallel orientation of neighboring atomic magnetic moments. Unlike antiferromagnets, neighboring oppositely directed magnetic moments, for some reason, do not completely compensate each other. The behavior of a ferrimagnet in an external field is in many ways similar to a ferromagnet, but the temperature dependence of the properties has a different form: sometimes there is a compensation point for the total magnetic moment at a temperature below the Néel point. By electrical properties ferromagnets - dielectrics or semiconductors.
Superparamagnetism- quasi-paramagnetic behavior of systems consisting of a collection of extremely small ferro- or ferrimagnetic particles. Particles of these substances, with definitely small sizes, transform into a single-domain state with uniform spontaneous magnetization throughout the entire volume of the particle. The combination of such substances behaves in relation to the influence of an external magnetic field and temperature like a paramagnetic gas (copper-cobalt alloys, fine nickel powders, etc.).
Superparamagnetism used in fine structural studies, in methods of non-destructive determination of sizes, shapes, quantity and composition of the magnetic phase, etc.
Piezomagnets- substances in which, when elastic stresses are applied, a spontaneous magnetic effect occurs, proportional to the first power of the stress magnitude. This effect is very small and is easiest to detect in antiferromagnets.
Magnetoelectrics- substances in which, when placed in an electric field, a magnetic moment appears that is proportional to the field value.
21) Harmonic vibrations. Conditions, characteristics, equation, graphs.
Harmonic vibrations- oscillations in which a physical (or any other) quantity changes over time according to a sinusoidal or cosine law. The kinematic equation of harmonic oscillations has the form
where x is the displacement (deviation) of the oscillating point from the equilibrium position at time t; A is the amplitude of oscillations, this is the quantity that determines maximum deviation oscillating point from the equilibrium position; ω - cyclic frequency, a value indicating the number of complete oscillations occurring within 2π seconds; - full phase of oscillations, - initial phase hesitation.
Generalized harmonic oscillation in differential form: 
Let us consider an isolated atom not subject to the action of an external magnetic field. According to ideas classical physics, electrons in atoms move in some closed orbits. This movement of each electron is equivalent to a closed current loop. Therefore, any atom or molecule, from the point of view of their magnetic properties, can be considered as a certain set of electronic microcurrents. This is Ampere's hypothesis about the nature of magnetism.
The magnetic moment p m of the electric current caused by the motion of an electron in orbit is called the orbital magnetic moment of the electron. Let us assume for simplicity that an electron in an atom moves at a speed v in a circular orbit of radius r(rice.).
According to the definition of the magnetic moment of a current, the orbital magnetic moment of an electron is numerically equal to
where S is the area of the electron orbit. Vector p m is directed in the same direction as the magnetic field at the center of the circular current.
The properties that substances exhibit in a magnetic field are called magnetic, and the substances themselves are called magnets. The magnetic properties of substances are determined by the presence of magnetic moments in their atoms. For most elements, in the absence of an external magnetic field, the magnetic moments of the electrons entering the atoms are equal to zero, since they have different directions and completely compensate each other. The application of an external magnetic field leads to a reorientation of the moments of magnetic atoms and the appearance of a non-zero magnetic moment. In this case, the non-zero total magnetic moment changes the magnetic field.
When studying the magnetic field in a substance (magnet), two types of currents are distinguished - macrocurrents and microcurrents. Under macrocurrents understand electrical conduction currents, as well as convection currents associated with the movement of charged macroscopic bodies. Microcurrents or molecular currents are currents caused by the movement of electrons in atoms, ions and molecules.
In a substance, an additional magnetic field of microcurrents (respectively called internal) is superimposed on the magnetic field of macrocurrents (it is often called external). The magnetic induction vector B characterizes the resulting magnetic field in the substance, i.e. it is equal to geometric sum magnetic induction external (Во) and internal (В int) fields:
Those. vector B must depend on the magnetic properties of the magnet. The magnetic field of microcurrents arises as a result of magnetization of a magnet when it is placed in an external magnetic field. Therefore, the primary source of the magnetic field in matter is macrocurrents.
Since in a vacuum the field is created only by macrocurrents, and in matter - by macrocurrents and microcurrents, then for the field in matter total current law looks like
(13.1.1)
where I macro and I micro - algebraic sums respectively, macro- and microcurrents covered by a closed circuit L, i.e., the resulting macro- and microcurrents through the surface formed by the circuit L.
The quantity H, which depends on the magnetic properties of the medium, is called magnetic field strength.
The unit of measurement for magnetic field strength is A/m. If the directions of the magnetization vectors and magnetic field strength coincide, then the substances are called isotropic magnets. If the direction of the magnetization vector depends on the direction of the field relative to the crystallographic axes, then the substances are anisotropic magnets. Graphically, the magnetic field strength is depicted using lines, the tangent to which at each point coincides with the direction of the strength at that point. The density of these lines is proportional to the magnitude of the tension vector. Unlike the magnetic induction vector, the lines of the H vector begin and end at the interface between two substances with different magnetic properties.
Diamagnets are substances whose magnetic moments of atoms or molecules are equal to zero in the absence of an external magnetic field, i.e. in atoms or molecules of diamagnetic substances, the vector sum of the orbital magnetic moments of all electrons is zero. Diamagnets are inert gases, majority organic compounds, many metals (bismuth, zinc, gold, copper, silver, mercury, etc.), resins, water, glass, marble.
When a diamagnetic substance is introduced into a magnetic field, a magnetic moment ΔР m is induced in each of its atoms, directed opposite to the vector B of the magnetic field induction.
To characterize the magnetization of a substance, we introduce physical quantity, called the magnetization intensity.
Magnetization vector or magnetization intensity J is the ratio of the magnetic moment of a small volume ΔV of a substance to this volume
where P mi is the magnetic moment i th molecule, n - total number molecules in volume ΔV. The volume ΔV must be so small that within its limits the magnetic field can be considered uniform. IN International system units (SI) the magnetization vector is measured in amperes per meter (A/m).
If a certain body is introduced into a uniform magnetic field of strength H 0 in a medium with permeability μ 1, then the magnetic field strength inside this body H will be equal to the sum of the strengths of the external (initial) field H 0 and the field H m created by the molecular currents of the body:
Н= Н 0 + Н m,
where N m is called demagnetization field. This field depends on the coordinates of the point of the body under consideration, its shape and orientation relative to the external field.
Magnetic induction B in a magnet determined by the sum of the field created external sources, and the fields of magnetic moments of the magnet itself:
Where does the magnetic field strength come from?
Magnetic permeability in contrast to dielectric constant can be either greater or less than one. For diamagnetic materials μ<1, а у парамагнетиков μ>1.
If the vector sum of the orbital magnetic moments of all electrons of an atom (or molecule) is not equal to zero, then the atom as a whole has a certain magnetic moment Р m. Such atoms (molecules) are called paramagnetic, and the substances consisting of them are called paramagnetic. Paramagnetic materials include oxygen, nitric oxide, aluminum, platinum, and other substances.
In paramagnets, the magnetization vector is directed along the applied field. In this case, the magnetic moments of atoms and molecules are different from zero, but are directed chaotically. When an external magnetic field is applied, their directions are redistributed. The number of magnetic moments approaching the magnetic field turns out to be predominant. This leads to the appearance of a nonzero magnetization directed along the field induction vector.
Unlike diamagnetic materials, paramagnetic materials have magnetic susceptibility that strongly depends on temperature.
For many paramagnetic substances, the change in magnetic susceptibility with temperature obeys the law established by Curie:
where T – thermodynamic temperature, C is the Curie constant, depending on the type of substance.
Classical theory paramagnetism was developed by P. Langevin in 1905. He considered statistical problem on the behavior of molecular currents (and the corresponding magnetic moments P m) in a uniform magnetic field. The orienting effect of a magnetic field on an atom depends on the magnetic moment of the atom and the magnetic induction B of the field.
Over the past 50 years, all branches of science have stepped forward rapidly. But after reading many journals about the nature of magnetism and gravity, one can come to the conclusion that a person has even more questions than before.
The nature of magnetism and gravity
It is obvious and clear to everyone that objects thrown up quickly fall to the ground. What attracts them? We can safely assume that they are attracted by some unknown forces. Those same forces are called natural gravity. Afterwards, everyone interested is faced with many disputes, guesses, assumptions and questions. What is the nature of magnetism? What are they? As a result of what influence are they formed? What is their essence and frequency? How do they affect environment and for each person separately? How can this phenomenon be rationally used for the benefit of civilization?
Magnetism concept
At the beginning of the nineteenth century, physicist Oersted Hans Christian discovered the magnetic field of electric current. This made it possible to assume that the nature of magnetism is closely related to the electric current that is formed inside each of the existing atoms. The question arises: what phenomena can explain the nature of terrestrial magnetism?
Today it has been established that magnetic fields in magnetized objects originate in to a greater extent electrons that continuously rotate around their axis and around the nucleus of an existing atom.
It has long been established that the chaotic movement of electrons is a real electric current, and its passage provokes the generation of a magnetic field. To summarize this part, we can safely say that electrons, due to their chaotic movement within atoms, generate intra-atomic currents, which, in turn, contribute to the generation of a magnetic field.
But what is the reason for the fact that in different matter the magnetic field has significant differences in its own value, as well as different strength magnetization? This is due to the fact that the axes and orbits of movement of independent electrons in atoms can be in various positions relative to each other. This leads to the fact that the magnetic fields produced by moving electrons are located in appropriate positions.
Thus, it should be noted that the environment in which the magnetic field is generated has an impact directly on it, increasing or weakening the field itself.
The field of which weakens the resulting field is called diamagnetic, and materials that very weakly enhance the magnetic field are called paramagnetic.
Magnetic properties of substances
It should be noted that the nature of magnetism is generated not only by electric current, but also by permanent magnets.
Permanent magnets can be made from small quantity substances on Earth. But it is worth noting that all objects that will be within the radius of the magnetic field will be magnetized and become immediate. After analyzing the above, it is worth adding that the magnetic induction vector in the presence of a substance differs from the vacuum magnetic induction vector.
Ampere's hypothesis on the nature of magnetism
The cause-and-effect relationship, as a result of which the connection between the possession of magnetic properties by bodies was established, was discovered by the outstanding French scientist Andre-Marie Ampère. But what is Ampere's hypothesis about the nature of magnetism?
The story began thanks to the strong impression of what the scientist saw. He witnessed the research of Ørsted Lmyer, who boldly suggested that the cause of the Earth's magnetism is the currents that regularly pass inside globe. The fundamental and most significant contribution was made: magnetic features bodies could be explained by the continuous circulation of currents in them. After Ampere put forward the following conclusion: the magnetic features of any of existing bodies determined by a closed circuit of electric currents flowing inside them. The physicist's statement was a bold and courageous act, since he crossed out all previous discoveries by explaining the magnetic properties of bodies.
Movement of electrons and electric current
Ampere's hypothesis states that within every atom and molecule there exists an elementary and circulating charge of electric current. It is worth noting that today we already know that those same currents are formed as a result of the chaotic and continuous movement of electrons in atoms. If the specified planes are located randomly relative to each other due to the thermal movement of molecules, then their processes are mutually compensated and have absolutely no magnetic features. And in a magnetized object, the simplest currents are aimed at ensuring that their actions are coordinated.
Ampere's hypothesis can explain why magnetic needles and frames with electric current in a magnetic field behave identically to each other. The arrow, in turn, should be considered as a complex of small circuits with current, which are directed identically.
A special group in which the magnetic field is significantly enhanced is called ferromagnetic. These materials include iron, nickel, cobalt and gadolinium (and their alloys).
But how to explain the nature of the magnetism of permanent magnets? Magnetic fields are formed by ferromagnets not only as a result of the movement of electrons, but also as a result of their own chaotic movement.
Momentum (intrinsic torque) acquired the name - spin. Electrons rotate around their axis throughout their entire existence and, having a charge, generate a magnetic field along with the field formed as a result of their orbital movement around the nuclei.
Marie Curie temperature
The temperature above which a ferromagnetic substance loses its magnetization received its specific name - the Curie temperature. After all, it was a French scientist with this name who made this discovery. He came to the conclusion: if you significantly heat a magnetized object, it will lose the ability to attract objects made of iron.
Ferromagnets and their use
Despite the fact that there are not many ferromagnetic bodies in the world, their magnetic features are very practical application and meaning. The core in the coil, made of iron or steel, multiplies the magnetic field, while not exceeding the current consumption in the coil. This phenomenon significantly helps save energy. The cores are made exclusively from ferromagnetic materials, and it does not matter for what purpose this part will be used.
Magnetic method of recording information
Ferromagnetic materials are used to produce first-class magnetic tapes and miniature magnetic films. Magnetic tapes are widely used in the fields of sound and video recording.
Magnetic tape is a plastic base consisting of polyvinylchloride or other components. A layer is applied on top of it, which is a magnetic varnish, which consists of many very small needle-shaped particles of iron or other ferromagnetic.
The sound recording process is carried out on tape due to the field of which is subject to changes in time due to sound vibrations. As a result of the movement of the tape near the magnetic head, each section of the film is subject to magnetization.
The nature of gravity and its concepts
It is worth noting first of all that gravity and its forces are contained within the law universal gravity, which states that: two material points attract each other with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Modern science has begun to consider concepts a little differently gravitational force and explains it as an action gravitational field The Earth itself, the origin of which, unfortunately for scientists, has not yet been established.
Summarizing all of the above, I would like to note that everything in our world is closely interconnected, and there is no significant difference between gravity and magnetism. After all, gravity has the same magnetism, just not to a large extent. On Earth, you cannot separate an object from nature - magnetism and gravity are disrupted, which in the future can significantly complicate the life of civilization. Should reap the benefits scientific discoveries great scientists and strive for new achievements, but all data should be used rationally, without causing harm to nature and humanity.
Any substance in the world has certain magnetic properties. They are measured by magnetic permeability. In this article we will look at the magnetic properties of matter.
Ampere's hypothesis
Magnetic permeability shows how many times the magnetic field induction in a given environment is less or greater than the magnetic field induction in a vacuum.
A substance that creates its own magnetic field is called magnetized. Magnetization occurs when a substance is placed in an external magnetic field.
The French scientist Ampere established the reason, the consequence of which is the possession of magnetic properties by bodies. Ampere's hypothesis states that there are microscopic electric currents inside a substance (an electron has its own magnetic moment, which has quantum nature, orbital movement electrons in atoms). It is they that determine the magnetic properties of a substance. If the currents have disordered directions, then the magnetic fields they generate cancel each other out. The body is not magnetized. An external magnetic field regulates these currents. As a result, the substance develops its own magnetic field. This is the magnetization of the substance.
It is precisely by the reaction of substances to an external magnetic field and by their ordering internal structure, determine the magnetic properties of a substance. In accordance with these parameters, they are divided into the following groups:
- Paramagnets
- Diamagnets
- Ferromagnets
- Antiferromagnets
Diamagnets and paramagnets
- Substances that have negative magnetic susceptibility, independent of the magnetic field strength, are called diamagnetic materials. Let's figure out what magnetic properties of a substance are called negative magnetic susceptibility. This is when a magnet is brought to a body, and it is repelled rather than attracted. Diamagnets include, for example, inert gases, hydrogen, phosphorus, zinc, gold, nitrogen, silicon, bismuth, copper, and silver. That is, these are substances that are in a superconducting state or have covalent bonds.
- Paramagnetic materials. For these substances, the magnetic susceptibility also does not depend on what field strength exists. She is positive though. That is, when a paramagnetic approaches a constant working magnet, an attractive force arises. These include aluminum, platinum, oxygen, manganese, iron.
Ferromagnets
Substances that have high positive magnetic susceptibility are called ferromagnets. For these substances, unlike diamagnetic and paramagnetic materials, the magnetic susceptibility depends on temperature and magnetic field strength, and to a significant extent. These include nickel and cobalt crystals.
Antiferromagnets and ferrimagnets
- Substances that undergo heating when heated phase transition of this substance, accompanied by the appearance of paramagnetic properties, are called antiferromagnets. If the temperature becomes lower than a certain one, these properties of the substance will not be observed. Examples of these substances would be manganese and chromium.
- Ferrimagnets are characterized by the presence of uncompensated antiferromagnetism in them. Their magnetic susceptibility also depends on temperatures and magnetic field strength. But they still have differences. These substances include various oxides.
All of the above magnets can be further divided into 2 categories:
- Hard magnetic materials. These are materials from high value coercive force. To remagnetize them, it is necessary to create a powerful magnetic field. These materials are used in the manufacture of permanent magnets.
- Soft magnetic materials, on the contrary, have a low coercive force. In weak magnetic fields they are able to enter saturation. They have low losses due to magnetization reversal. Because of this, these materials are used to make cores for electrical machines that operate on alternating current. This is, for example, a current and voltage transformer, or a generator, or an asynchronous motor.
We looked at all the basic magnetic properties of matter and figured out what types of magnets exist.
