Magnetic flux designation and unit of measurement. Basic formulas. Unraveling the mystery of magnetic flux

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weber

Weber (Wb)

milliweber

Milliveber (mWb)
1 Wb = 1 V s = 1 T m² = 1 J/A = 10⁸ μs (Maxwellian).

microweber

Microweber (mWb)- a derived unit of measurement of magnetic flux in the SI system, which is a submultiple in relation to the Weber. By definition, a change in magnetic flux through a closed loop at a rate of one weber per second induces an electromotive force (EMF) equal to one volt in that loop. In other SI units, Weber is expressed as follows: tesla per square meter (T m²), or volt-second (V s), or joule per ampere (J/A).
1 Wb = 1 V s = 1 T m² = 1 J/A = 10⁸ μs (Maxwellian).

volt-second

Volt-second (V s)- derived unit of measurement of magnetic flux in the SI system. By definition, a change in magnetic flux through a closed loop at a rate of one weber per second induces an electromotive force (EMF) equal to one volt in that loop. In other SI units, Weber is expressed as follows: tesla per square meter (T m²), or volt-second (V s), or joule per ampere (J/A).
1 Wb = 1 V s = 1 T m² = 1 J/A = 10⁸ μs (Maxwellian).

single magnetic pole

Single magnetic pole(eng. unit magnetic pole) - a unit for measuring the force of interaction between two magnets in a vacuum, equal to the force with which one magnetic pole repels another magnetic pole of the same name at a distance of one centimeter with a force of one dyne. In SI units, a unit of magnetic flux can be defined as a pole which, when placed in a vacuum, at a distance of one meter from a like and equal pole, repels it with a force of ¼πμ₀ newtons, where μ₀ is the absolute magnetic permeability of vacuum or air 4π · 10⁻⁷ Gn/m. In the MKS (meter-kilogram-second system) and SI, this concept was replaced by the current flowing through the winding, that is, ampere-turns and, later, amperes.

megaline

Megaline

kiloline

kiloline- a unit of measurement of magnetic flux, a multiple of the line - the old name of Maxwell (Mks), which is a derived unit of measurement of magnetic flux in the CGS system. In a uniform magnetic field with an induction of one Gauss, a magnetic flux of one Maxwell passes through a flat contour with an area of ​​one square centimeter located perpendicular to the induction vector: 1 μs = 1 G cm² = 10⁻⁸ Wb

line

Line- the old name for Maxwell (Mks) - a derived unit of measurement of magnetic flux in the CGS system. In a uniform magnetic field with an induction of one Gauss, a magnetic flux of one Maxwell passes through a flat contour with an area of ​​one square centimeter located perpendicular to the induction vector: 1 μs = 1 G cm² = 10⁻⁸ Wb

Maxwell

Maxwell (Mks)- a derived unit of measurement of magnetic flux in the GHS system. In a uniform magnetic field with an induction of one Gauss, a magnetic flux of one Maxwell passes through a flat contour with an area of ​​one square centimeter, located perpendicular to the induction vector: 1 μs = 1 G cm² = 10⁻⁸ Wb. Maxwell was previously called a line.

tesla meter²

Tesla square meter (T m²)- unit of magnetic flux equal to Weber (Wb). By definition, a change in magnetic flux through a closed loop at a rate of one weber per second induces an electromotive force (EMF) equal to one volt in that loop. In other SI units, Weber is expressed as follows: tesla per square meter (T m²), or volt-second (V s), or joule per ampere (J/A).
1 Wb = 1 V s = 1 T m² = 1 J/A = 10⁸ μs (Maxwellian).

tesla-centimeter²

Tesla-square centimeter (T cm²)- unit of measurement of magnetic flux, multiple of Weber (Wb). By definition, a change in magnetic flux through a closed loop at a rate of one weber per second induces an electromotive force (EMF) equal to one volt in that loop. In other SI units, Weber is expressed as follows: tesla per square meter (T m²), or volt-second (V s), or joule per ampere (J/A).
1 Wb = 1 V s = 1 T m² = 1 J/A = 10⁸ μs (Maxwellian).

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Then the magnetic field induction lines will pass through this circuit. A magnetic induction line is the magnetic induction at each point on this line. That is, we can say that magnetic induction lines are the flow of the induction vector through the space limited and described by these lines. In short, magnetic flux can be said.

In general terms, the concept of “magnetic flux” is introduced in the ninth grade. A more detailed consideration with the derivation of formulas, etc., refers to the high school physics course. So, magnetic flux is a certain amount of magnetic field induction in any region of space.

Direction and amount of magnetic flux

Magnetic flux has a direction and a quantitative value. In our case, a circuit with current, we say that this circuit is penetrated by a certain magnetic flux. It is clear that the larger the circuit, the greater the magnetic flux will pass through it.

That is, magnetic flux depends on the area of ​​space through which it passes. If we have a fixed frame of a certain size, penetrated by a constant magnetic field, then the magnetic flux passing through this frame will be constant.

If we increase the strength of the magnetic field, then the magnetic induction will increase accordingly. The magnitude of the magnetic flux will also increase, and in proportion to the increased magnitude of induction. That is, the magnetic flux depends on the magnitude of the magnetic field induction and the area of ​​the surface being penetrated.

Magnetic flux and frame - consider an example

Let's consider the option when our frame is located perpendicular to the magnetic flux. The area limited by this frame will be maximum in relation to the magnetic flux passing through it. Consequently, the flux value will be maximum for a given magnetic field induction value.

If we begin to rotate the frame relative to the direction of the magnetic flux, then the area through which the magnetic flux can pass will decrease, therefore, the amount of magnetic flux through this frame will decrease. Moreover, it will decrease down to zero when the frame becomes parallel to the lines of magnetic induction.

The magnetic flux will seem to slide past the frame, it will not penetrate it. In this case, the effect of the magnetic field on the current-carrying frame will be zero. Thus we can derive the following dependency:

The magnetic flux penetrating the area of ​​the circuit changes when the magnitude of the magnetic induction vector B, the area of ​​the circuit S changes, and when the circuit rotates, that is, when its orientation to the magnetic field induction lines changes.

Magnetic materials are those that are subject to the influence of special force fields, in turn, non-magnetic materials are not subject or weakly subject to the forces of a magnetic field, which is usually represented by lines of force (magnetic flux) having certain properties. In addition to always forming closed loops, they behave as if they were elastic, that is, during distortion they try to return to their previous distance and to their natural shape.

Invisible Power

Magnets tend to attract certain metals, especially iron and steel, as well as nickel, nickel, chromium and cobalt alloys. Materials that create attractive forces are magnets. There are different types of them. Materials that can be easily magnetized are called ferromagnetic. They can be hard or soft. Soft ferromagnetic materials, such as iron, quickly lose their properties. Magnets made from these materials are called temporary. Hard materials such as steel hold their properties much longer and are used permanently.

Magnetic flux: definition and characteristics

There is a certain force field around the magnet, and this creates the possibility of energy. The magnetic flux is equal to the product of the average force fields perpendicular to the surface into which it penetrates. It is represented by the symbol "Φ" and is measured in units called Webers (WB). The amount of flow passing through a given area will vary from one point to another around the object. Thus, magnetic flux is a so-called measure of the strength of a magnetic field or electric current based on the total number of charged lines of force passing through a certain area.

Unraveling the mystery of magnetic flux

All magnets, regardless of their shape, have two areas called poles that are capable of producing a certain chain of organized and balanced system of invisible lines of force. These lines from the flow form a special field, the shape of which appears more intense in some parts compared to others. The regions with the greatest attraction are called poles. Vector field lines cannot be detected with the naked eye. Visually, they always appear as lines of force with unambiguous poles at each end of the material, where the lines are denser and more concentrated. Magnetic flux is lines that create vibrations of attraction or repulsion, showing their direction and intensity.

Magnetic flux lines

Magnetic field lines are defined as curves that move along a specific path in a magnetic field. The tangent to these curves at any point shows the direction of the magnetic field at that point. Characteristics:

Each flow line forms a closed loop.

These induction lines never intersect, but tend to shorten or stretch, changing their dimensions in one direction or another.

As a rule, field lines have a beginning and an end at the surface.

There is also a specific direction from north to south.

Lines of force that are located close to each other, forming a strong magnetic field.

• When adjacent poles are the same (north-north or south-south), they repel each other. When adjacent poles are not aligned (north-south or south-north), they are attracted to each other. This effect is reminiscent of the famous saying that opposites attract.

Magnetic molecules and Weber's theory

Weber's theory relies on the fact that all atoms have magnetic properties due to the bond between electrons in the atoms. Groups of atoms bond together in such a way that the fields surrounding them rotate in the same direction. These kinds of materials are made up of groups of tiny magnets (when viewed at the molecular level) around atoms, meaning that a ferromagnetic material is made up of molecules that have attractive forces. These are known as dipoles and are grouped into domains. When the material is magnetized, all domains become one. A material loses its ability to attract and repel if its domains become separated. The dipoles together form a magnet, but individually each of them tries to push away from the unipolar one, thus attracting opposite poles.

Fields and poles

The strength and direction of the magnetic field are determined by magnetic flux lines. The area of ​​attraction is stronger where the lines are close to each other. The lines are closest to the pole of the rod base, where the attraction is strongest. Planet Earth itself is located in this powerful force field. It acts as if a giant magnetized stripe plate were passing through the middle of the planet. The north pole of the compass needle points towards a point called the North Magnetic Pole, and the south pole points towards magnetic south. However, these directions are different from the geographic North and South Poles.

The nature of magnetism

Magnetism plays an important role in electrical and electronics engineering because without its components such as relays, solenoids, inductors, chokes, coils, loudspeakers, electric motors, generators, transformers, electricity meters, etc. will not work. Magnets can be found in natural state in the form of magnetic ores. There are two main types, magnetite (also called iron oxide) and magnetic iron ore. The molecular structure of this material in a non-magnetic state is presented in the form of a free magnetic chain or individual tiny particles that are freely arranged in a random order. When a material is magnetized, this random arrangement of molecules changes, and the tiny random molecular particles line up in such a way that they produce a whole series of arrangements. This idea of ​​molecular alignment of ferromagnetic materials is called Weber's theory.

Measurement and practical application

The most common generators use magnetic flux to produce electricity. Its power is widely used in electrical generators. The instrument used to measure this interesting phenomenon is called a fluxmeter, which consists of a coil and electronic equipment that measures the change in voltage across the coil. In physics, flux is an indicator of the number of lines of force passing through a certain area. Magnetic flux is a measure of the number of magnetic lines of force.

Sometimes even a non-magnetic material can also have diamagnetic and paramagnetic properties. An interesting fact is that the forces of attraction can be destroyed by heating or striking with a hammer of the same material, but they cannot be destroyed or isolated by simply breaking a large specimen into two parts. Each broken piece will have its own north and south pole, no matter how small the pieces are.

Electric dipole moment
Electric charge
Electrical induction
Electric field
Electrostatic potential

Magnetostatics
Biot-Savart-Laplace law Ampere's law Magnetic moment A magnetic field Magnetic flux Magnetic induction

Electrodynamics
Vector potential Dipole Lienard-Wiechert potentials Lorentz force Bias current Unipolar induction Maxwell's equations Electricity Electromotive force Electromagnetic induction Electromagnetic radiation Electromagnetic field

Electrical circuit
Ohm's law Kirchhoff's laws Inductance Radio waveguide Resonator Electrical capacity Electrical conductivity Electrical resistance Electrical impedance

Famous scientists
Henry Cavendish Michael Faraday Nikola Tesla Andre-Marie Ampère Gustav Robert Kirchhoff James Clerk (Clark) Maxwell Henry Rudolf Hertz Albert Abraham Michelson Robert Andrews Milliken

See also: Portal:Physics

Magnetic flux- physical quantity equal to the product of the magnitude of the magnetic induction vector $\backslash vec\; B$ by area S and cosine of angle α between vectors $\backslash vec\; B$ and normal $\backslash mathbf(n)$. Flow $\backslash Phi\_B$ as the integral of the magnetic induction vector $\backslash vec\; B$ through end surface S is determined through the surface integral:

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In this case, the vector element d S surface area S is defined as

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Magnetic flux quantization

Values ​​of magnetic flux Φ passing through

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An excerpt characterizing Magnetic Flux

“C"est bien, mais ne demenagez pas de chez le prince Vasile. Il est bon d"avoir un ami comme le prince,” she said, smiling at Prince Vasily. - J"en sais quelque chose. N"est ce pas? [That's good, but don't move away from Prince Vasily. It's good to have such a friend. I know something about this. Isn't that right?] And you are still so young. You need advice. Don't be angry with me for taking advantage of old women's rights. “She fell silent, as women always remain silent, expecting something after they say about their years. – If you get married, then it’s a different matter. – And she combined them into one look. Pierre did not look at Helen, and she did not look at him. But she was still terribly close to him. He mumbled something and blushed.
Returning home, Pierre could not fall asleep for a long time, thinking about what happened to him. What happened to him? Nothing. He just realized that the woman he knew as a child, about whom he absentmindedly said: “Yes, she’s good,” when they told him that Helen was beautiful, he realized that this woman could belong to him.
“But she’s stupid, I said myself that she’s stupid,” he thought. “There is something nasty in the feeling that she aroused in me, something forbidden.” They told me that her brother Anatole was in love with her, and she was in love with him, that there was a whole story, and that Anatole was sent away from this. Her brother is Hippolytus... Her father is Prince Vasily... This is not good,” he thought; and at the same time as he reasoned like this (these reasonings still remained unfinished), he found himself smiling and realized that another series of reasoning was emerging from behind the first, that at the same time he was thinking about her insignificance and dreaming about how she will be his wife, how she can love him, how she can be completely different, and how everything that he thought and heard about her may not be true. And again he saw her not as some daughter of Prince Vasily, but saw her whole body, only covered with a gray dress. “But no, why didn’t this thought occur to me before?” And again he told himself that this was impossible; that something disgusting, unnatural, as it seemed to him, would be dishonest in this marriage. He remembered her previous words, looks, and the words and looks of those who saw them together. He remembered the words and looks of Anna Pavlovna when she told him about the house, he remembered thousands of such hints from Prince Vasily and others, and horror came over him, whether he had already tied himself in some way in carrying out such a task, which was obviously not good and which he should not do. But at the same time, as he expressed this decision to himself, from the other side of his soul her image emerged with all its feminine beauty.

In November 1805, Prince Vasily was supposed to go to an audit in four provinces. He arranged this appointment for himself in order to visit his ruined estates at the same time, and taking with him (at the location of his regiment) his son Anatoly, he and him would go to Prince Nikolai Andreevich Bolkonsky in order to marry his son to the daughter of this rich man old man. But before leaving and these new affairs, Prince Vasily needed to resolve matters with Pierre, who, however, had recently been spending whole days at home, that is, with Prince Vasily, with whom he lived, he was funny, excited and stupid (as he should to be in love) in the presence of Helen, but still did not propose.

Among physical quantities, magnetic flux occupies an important place. This article explains what it is and how to determine its size.

What is magnetic flux

This is a quantity that determines the level of the magnetic field passing through the surface. It is designated “FF” and depends on the strength of the field and the angle of passage of the field through this surface.

It is calculated according to the formula:

FF=B⋅S⋅cosα, where:

• FF – magnetic flux;
• B is the magnitude of magnetic induction;
• S is the surface area through which this field passes;
• cosα is the cosine of the angle between the perpendicular to the surface and the flow.

The SI unit of measurement is “weber” (Wb). 1 Weber is created by a field of 1 Tesla passing perpendicular to a surface with an area of ​​1 m².

Thus, the flow is maximum when its direction coincides with the vertical and is equal to “0” if it is parallel to the surface.

Interesting. The magnetic flux formula is similar to the formula by which illumination is calculated.

Permanent magnets

One of the field sources is permanent magnets. They have been known for many centuries. The compass needle was made from magnetized iron, and in Ancient Greece there was a legend about an island that attracted metal parts of ships.

Permanent magnets come in various shapes and are made from different materials:

• iron ones are the cheapest, but have less attractive force;
• neodymium - made from an alloy of neodymium, iron and boron;
• Alnico is an alloy of iron, aluminum, nickel and cobalt.

All magnets are bipolar. This is most noticeable in rod and horseshoe devices.

If the rod is suspended from the middle or placed on a floating piece of wood or foam, it will turn in the north-south direction. The pole pointing north is called the north pole and is painted blue on laboratory instruments and designated “N.” The opposite one, pointing south, is red and marked “S”. Magnets with like poles attract, and with opposite poles they repel.

In 1851, Michael Faraday proposed the concept of closed induction lines. These lines come out of the north pole of the magnet, pass through the surrounding space, enter the south and return to the north inside the device. The lines and field strength are closest at the poles. The attractive force is also higher here.

If you put a piece of glass on the device and sprinkle iron filings on top in a thin layer, they will be located along the magnetic field lines. When several devices are placed nearby, the sawdust will show the interaction between them: attraction or repulsion.

Earth's magnetic field

Our planet can be imagined as a magnet, the axis of which is inclined by 12 degrees. The intersections of this axis with the surface are called magnetic poles. Like any magnet, the Earth's lines of force run from the north pole to the south. Near the poles they run perpendicular to the surface, so there the compass needle is unreliable, and other methods have to be used.

Particles of the “solar wind” have an electric charge, so when moving around them, a magnetic field appears, interacting with the Earth’s field and directing these particles along the lines of force. Thus, this field protects the earth's surface from cosmic radiation. However, near the poles these lines are directed perpendicular to the surface, and charged particles enter the atmosphere, causing the northern lights.

In 1820, Hans Oersted, while conducting experiments, saw the effect of a conductor through which an electric current flows on a compass needle. A few days later, Andre-Marie Ampere discovered the mutual attraction of two wires through which a current flowed in the same direction.

Interesting. During electric welding, nearby cables move when the current changes.

Ampere later suggested that this was due to the magnetic induction of current flowing through the wires.

In a coil wound with an insulated wire through which electric current flows, the fields of the individual conductors reinforce each other. To increase the attractive force, the coil is wound on an open steel core. This core is magnetized and attracts iron parts or the other half of the core in relays and contactors.

Electromagnetic induction

When the magnetic flux changes, an electric current is induced in the wire. This fact does not depend on what causes this change: the movement of a permanent magnet, the movement of a wire, or a change in the current strength in a nearby conductor.

This phenomenon was discovered by Michael Faraday on August 29, 1831. His experiments showed that the EMF (electromotive force) appearing in a circuit bounded by conductors is directly proportional to the rate of change of flux passing through the area of ​​this circuit.

Important! For an emf to occur, the wire must cross the power lines. When moving along the lines, there is no EMF.

If the coil in which the EMF occurs is connected to an electrical circuit, then a current arises in the winding, creating its own electromagnetic field in the inductor.

When a conductor moves in a magnetic field, an emf is induced in it. Its direction depends on the direction of movement of the wire. The method by which the direction of magnetic induction is determined is called the “right-hand method”.

Calculating the magnitude of the magnetic field is important for the design of electrical machines and transformers.

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