Under the term "magnetic field" it is customary to mean a certain energy space in which the forces of magnetic interaction are manifested. They affect:

separate substances: Ferrimagnetics (metals are predominantly cast iron, iron and alloys of them) and their class of ferrite, regardless of the state;

moving electricity charges.

Physical bodies possessing the total magnetic moment of electrons or other particles call permanent magnets. Their interaction is presented in the picture. power magnetic lines.

They were formed after bringing a permanent magnet to the opposite side of the cardboard sheet with a smooth layer of iron sawdust. The picture demonstrates a clear marking of the northern (N) and southern (s) poles with the direction of power lines regarding their orientation: exit from the North Pole and the entrance to the south.

How to create a magnetic field

Sources magnetic field are:

permanent magnets;

moving charges;

moving electric field.

With the action of permanent magnets, each child of kindergarten is familiar. After all, he had to sculpt on the refrigerator clip art magnets, removed from packages with all sorts of delicacies.

Movement electrical charges usually have a significantly greater magnetic field energy than. It is also denoted by the power lines. We will analyze their instructions for a straight conductor with current I.

The magnetic power line is carried out in the plane perpendicular to the current movement so that at each its point the force acting on the northern pole of the magnetic arrow, sent by tangent to this line. Thus, concentric circles around the moving charge are created.

The direction of these forces is determined by the well-known rules of the screw or a row with a right-handed-sided thread.

Rule Braschik

It is necessary to arrange the Brascap coaxially with the current vector and rotate the handle so that the progressive movement of the support coincides with its direction. Then the orientation of the power magnetic lines will be shown by the rotation of the handle.

In the ring conductor, the rotational movement of the handle coincides with the direction of the current, and the translational - indicates the orientation of the induction.

Magnetic power lines always come out of the North Pole and are included in the South. They continue inside the magnet and are never open.

Magnetic field interaction rules

Magnetic fields from different sources are folded with each other, forming a resulting field.

At the same time, magnets with multi-poles (N - S) are attracted to each other, and with the same name (N - N, S - S) - repel. The interaction forces between the poles depend on the distance between them. The closer the pole is shifted, the greater the effort arises.

Main characteristics of the magnetic field

These include:

vector magnetic induction (B);

magnetic stream (f);

flow (ψ).

Intensity or field effects are evaluated by the value vector magnetic induction. It is determined by the value of the force "F" created by the undergoing current "I" on the conductor with a length "L". B \u003d f / (i ∙ L)

The unit of measurement of magnetic induction in the SI-Tesla system (as a sign of the memory of the physics, which investigated these phenomena and described them with mathematical methods). In Russian technical literature, it is indicated by "TL", and the symbol "T" is adopted in international documentation.

1 TL is the induction of such a homogeneous magnetic flux, which acts with force in 1 Newton to each meter of the length of the straight line conductor, perpendicular to the direction of the field, when a current of 1 ampere passes through this conductor.

1TL \u003d 1 ∙ N / (A ∙ M)

The direction of the vector B is determined by relief left hand.

If you position the palm of the left hand in the magnetic field so that the power lines from the North Pole entered the palm at right angles, and the four fingers are located in the direction of current in the conductor, then the thumb finger will indicate the direction of force to this conductor.

In the case when an electric current conductor is located not at a right angle to magnetic power lines, the force acting on it will be proportional to the magnitude of the flowing current and the component of the projection of the conductor length with the current to the plane located in the perpendicular direction.

The force acting on the electric current does not depend on the materials from which the conductor and the area of \u200b\u200bits cross section are created. Even if this conductor does not work at all, and the moving charges will be moved to another medium between the magnetic poles, then this force will not change.

If inside the magnetic field at all points the vector B has the same direction and the value, then such a field is considered uniform.

Any medium that has an impact on the value of the induction vector.

Magnetic stream (f)

If we consider the passage of magnetic induction through a certain area S, the induction bounded by it will be called a magnetic flow.

When the area is inclined under some kind of angle α to the direction of magnetic induction, the magnetic flux decreases by the cosine of the angle of inclination area. The maximum value of its value is created with perpendicular location of the area to its permeating induction. F \u003d in · s

The unit of measurement of the magnetic flux is 1 Weber, determined by the passage of induction in 1 tesle through an area of \u200b\u200b1 meter square.

Flow

This term is used to obtain the total magnitude of the magnetic flux created from a certain number of conductors with a current located between the poles of the magnet.

For the case when the same current I passes through the winding of the coil with the number of turns N, then the full (adhesive) magnetic flux from all turns is called streaming ψ.

Ψ \u003d n · f . The unit of measurement of the stream is 1 Weber.

How the magnetic field is formed from the variable electric

The electromagnetic field interacting with electrical charges and bodies with magnetic moments is a combination of two fields:

electric;

magnetic.

They are interrelated, represent a totality of each other and with a change during the time of one, certain deviations occur in the other. For example, when creating an alternating sinusoidal electric field, a three-phase generator simultaneously forms the same magnetic field with the characteristics of similar alternating harmonics.

Magnetic properties Substances

In relation to the interaction with the outer magnetic field, the substance is divided into:

antiferromagnetics with balanced magnetic moments, which creates a very small degree of body magnetization;

diamagnetics with the magnetization property of the indoor field against the action of external. When there is no external field, then they do not show magnetic properties;

paramagnetics with the properties of the magnetization of the indoor field in the direction of external, which have a low degree;

ferromagnets with magnetic properties without an applied external field at temperatures less than the values \u200b\u200bof the Curie point;

ferrimagnetics with unbalanced in size and direction of magnetic moments.

All these properties of substances found a variety of use in modern techniques.

Magnetic chains

Based on all transformers, inductors, electrical machines and many other devices.

For example, in a working electromagnet, the magnetic stream passes through the magnetic pipeline of ferromagnetic steels and air with severe non-ferromagnetic properties. The combination of these elements is a magnetic chain.

Most electrical apparatus in their design have magnetic chains. Read more about this in this article -

Just as the resting electric charge acts on another charge by means of an electric field, the electric current acts on another current through magnetic field. The effect of the magnetic field on permanent magnets is reduced to the action of it on charges moving in the atoms of the substance and creating microscopic circular currents.

Doctrine by electromagnetism Based on two positions:

• the magnetic field acts on moving charges and currents;
• the magnetic field occurs around currents and moving charges.

Magnet interaction

Permanent magnet (or magnetic arrow) oriented along the magnetic meridian of the Earth. He is his end that indicates north is called north Pole (N), and the opposite end - south Pole (S). Approaching two magnets to each other, we note that their poles the same name are repelled, and the variepetes are attracted ( fig. one ).

If divided the poles, cutting a permanent magnet into two parts, then we will find that each of them will also have two poles, i.e. it will be a permanent magnet ( fig. 2. ). Both poles are north and southern, - inseparable from each other, equal.

The magnetic field created by the earth or permanent magnets is depicted, like an electric field, magnetic power lines. The picture of the power lines of the magnetic field of a magnet can be obtained by placing a sheet of paper over it, on which the iron sawdust is bottled. Finding into a magnetic field, the sawdust is magnetized - each of them appears northern and south Poles.. The opposite poles tend to get close to each other, but friction of sawdust on paper prevents this. If you knock on paper with your finger, friction will decrease and sawdust will be attracted to each other, forming chains depicting the magnetic field lines.

On the fig. 3. The location in the direct magnet of sawdust and small magnetic arrows indicating the direction of the magnetic field lines. For this direction, the direction of the North Pole of the magnetic arrow is taken.

Ersted's experience. Tok magnetic field

At the beginning of the XIX century. Danish scientist Erstead made an important discovery by finding electric current action for permanent magnets . He placed the long wire near the magnetic arrow. When the current passage, the arrow rotated, seeking to settle down perpendicular to him ( fig. four ). This could be explained by the occurrence around the conductor of the magnetic field.

Magnetic power lines of the field created by a direct conductor with a current are concentric circles located in the plane perpendicular to it, with centers at a point through which the current passes ( fig. five ). The direction of lines is determined by the rule of the right screw:

If the screw rotate in the direction of the field lines, it will move towards the current in the conductor .

The power characteristic of the magnetic field is vector magnetic induction B . At each point, it is directed by the field tangent. The lines of the electric field begin on positive charges and ends on the negative, and the force acting in this field to the charge is directed along the tangent of the line at each point. Unlike the electrical, the magnetic field line is closed, which is associated with the absence of "magnetic charges" in the nature.

The magnetic field of the current does not differ in principle from the field created by a permanent magnet. In this sense, an analogue of a flat magnet is a long solenoid - a coil from the wire, the length of which is much greater than its diameter. The diagram of the lines of the magnetic field created by it, depicted on Fig. 6. , similar to that for a flat magnet ( fig. 3. ). Circles indicate the cross sections of the wire forming the solenoid winding. The currents flowing on the wire from the observer are denoted by the cross, and the currents of the opposite direction - to the observer - are indicated by points. The same designations are accepted for the magnetic field lines, when they are perpendicular to the drawing plane ( fig. 7. A, b).

The direction of the current in the solenoid winding and the direction of the magnetic field lines inside it is also linked by the rule of the right screw, which in this case is formulated as follows:

If you look along the axis of the solenoid, then the current circuit board creates a magnetic field in it, the direction of which coincides with the direction of the right screw movement ( fig. 8 )

Based on this rule, it is easy to figure out that the solenoid depicted on Fig. 6. , the North Pole serves his right end, and the southern one is left.

The magnetic field inside the solenoid is homogeneous - the magnetic induction vector has a constant value (B \u003d const). In this regard, the solenoid is similar to a flat condenser, inside which a homogeneous electric field is created.

Power acting in a magnetic field on a conductor with current

Experienced it was found that the force on the conductor with a current in the magnetic field. In a uniform field, a straight line conductor L Lena, according to which the current I flows, located perpendicular to the field B vector, is experiencing force: F \u003d i l b .

The direction of force is determined rule of left hand:

If the four elongated fingers of the left hand are located in the direction of current in the explorer, and the palm is perpendicular to the vector B, then the retired thumb indicate the direction of force acting on the conductor (fig. nine ).

It should be noted that the force acting on the conductor with a current in the magnetic field is directed not by tangent of its power lines, like electrical strength, and perpendicular to them. On the conductor, located along the power lines, the magnetic force does not work.

The equation F \u003d ilb. Allows you to give a quantitative characteristic of the induction of the magnetic field.

Attitude It does not depend on the properties of the conductor and characterizes the magnetic field itself.

The module of the magnetic induction B is numerically equal to the power acting on a single-length conductor located perpendicular to it, according to which one amper strength flows.

In the system of the system of induction of the magnetic field serves Tesla (TL):

A magnetic field. Tables, Schemes, Formulas

(Magnet interaction, Ersted Experience, magnetic induction experience, vector direction, superposition principle. Graphic image of magnetic fields, magnetic induction line. Magnetic flow, energy characteristics. Magnetic forces, ampere power, Lorentz power. Movement of charged particles in a magnetic field. Magnetic Properties of matter, ampere hypothesis)

One of the numerous physical treatment methods is magnetic therapy, indications and contraindications of this therapeutic method should be extended well before starting the course of treatment. The magnetic field used in treatment is divided into static (permanent magnets) and dynamic. The dynamic magnetic field is caused by an electric shift in the conductor. Currently, it is widely used in the additional treatment of many diseases.

Magnetotherapy is a method of treatment using a magnetic field with a frequency of 0-50 Hz or 0-60 Hz and magnetic induction with values \u200b\u200bin the range from 0.5 to 10 (millibes). Therapy is carried out using a static and dynamic magnetic field.

In a static magnetic field, a major role is played by various kinds of magnets, which are currently not so often applied in treatment. Modern medicine Uses the therapeutic effects of the dynamic magnetic field (pulsed or alternating current) arising with the participation of the electric current passing through the conductor.

It has been scientifically proven that the deficiency of electromagnetic energy in the body is responsible for the slowdown in the process of metabolism, the transportation of nutrients and reduced operations nervous system. In addition, it is with a shortage of energy that arises a general decline in mood, performance and loss of human vital power.

Energy deficit can cause much more serious consequences For the health of the body. Such a state can provoke or strengthen the symptoms of heart disease, inflammatory processes, rheumatism as well neurological diseases And many other ailments.

It is proved that the most effective way Countering diseases caused by the lack of energy is magnetic therapy.

This method causes the ion shift, resulting in electronegability inside the cell, which allows more efficient absorption and use of oxygen. This process is called hyperpolarization.

The effect of the magnetic field is uniform, due to which the energy penetrates through all the tissues of the body, reaching the deepest layers. Magnetic therapy - the procedure is completely painless, not causing any side Effects Even in the perspective of long-term treatment. Sometimes at the beginning of therapy there is only a temporary and short-term complication of the symptoms of the disease.

How does the magnetic field act?

The use of the magnetic field causes changes in each cell and body tissue, as it penetrates through the entire body of the person. Any ions that are in cells and colloidal systems are sensitive and exposed to the magnetic field. The following processes occur under the magnetic field influence:

• rhythmic movement of ions in the cells of the human body;
• hyperpolarization of the cell membrane;
• beneficial effect on metabolism and energy processes.

The pulse magnetic field leads to:

• normalization of the electrical potential of the rest of the cell membrane;
• improving the dynamics of ions migrating through the membrane;
• improving the use of oxygen through the cell;
• enhance energy potential.

What treats a magnetic field?

Depending on the testimony and characteristics of the body in the treatment, a certain form of pulse (rectangular, triangular or sinusoidal) is selected. When treating the magnetic field, it is assumed that:

• rectangular impulses are applied at the moment when the pathological process extends to bone tissue;
• triangular form pulses are used in the treatment of articular cartilage, ligaments and tendons;
• sinusoidal pulses are used in situations when they require the treatment of muscle and nerves.

When and in what state of the disease can you apply a magnetic field? In the case of acute states of the disease, pulses frequencies are used from 1-5 Hz, the intensity of the magnetic field is 0.5-3 Mt (Milicel). In subacute states, treatment is carried out at a frequency of 5-20 Hz, the tension of the magnetic field 3-5 MT, with chronic painful states, frequencies are used from 20-50 Hz and the tension of the magnetic field of 6-10 MT.

It should be borne in mind that the magnetic field strength should be 40% of the maximum value of the adopted dose. During the 2nd course of treatment, its strength can be increased to 70%, and it is increased to a complete dose on the 3rd year of the procedures.

The time spent using a magnetic field can be from 15 to 30 minutes, but can last up to 1 hour. Procedures are performed by series from 15 to several tens of procedures. During the first 5 -10 procedures, therapy is used daily, and then can be carried out from 2-3 procedures during the week.

Who can, and who should not?

The principles of treatment with a magnetic field:

• treatment with a magnetic field should be carried out at the same time;
• procedures should not be used in the afternoon, or in the evening, due to the occurrence of drowsiness, while in the elderly, on the contrary, insomnia;
• the patient must take the clock and all metal objects before carrying out the procedure;
• when treating the magnetic field, it is not necessary to undress, you can stay in clothes.

Indications for the procedure of the magnetic field are the following:

• degenerative diseases of large joints (limbs) and spinal joints;
• inflammation of the joints and the near-hand fabrics;
• rheumatoid arthritis (RA);
• post-traumatic states and sports injuries: fractures (odeka disease), dislocations, stretching with muscle damage, ligaments and articular bags;
• difficult to heal wounds, burns;
• disorders of peripheral blood circulation;
• inflammation of the nerves (for example, neuralgia of the sedlication nerve);
• osteoporosis;
• metabolic disorders;
• bronchitis and sinusitis of the nose sinuses;
• inflammation of the ovaries;
• ulcers and trophic changes of the heads.

The procedures using the magnetic field are safe.

The use of procedures even for a very long time does not cause adverse effects.

It should, however, keep in mind that it is possible to exacerbate diseases after the first few procedures, which pass over time.

Significant relief for patients is the possibility of using magnetic therapy during injuries without removing the bandage, and even gypsum.

The most common contraindications for treatment with a magnetic field include:

• pregnancy;
• cancer diseases;
• treatment with ionizing radiation (radiation therapy) and radiological studies;
• implanted electronic implants, for example, a pacemaker;
• severe heart disease and cardiovascular system;
• refriterating thrombophlebitis;
• tendency to bleeding;
• active tuberculosis;
• acute bacterial and viral infections;
• diabetes;
• thyrotoxicosis;
• epilepsy;
• ringworm.

Magnetotherapy has many applications and a slight number of contraindications. Do not use magnetic therapy and in the case of severe systemic diseases.

Therapy of the magnetic field is invaluable in the fight against long pain. Indicates excellent anti-inflammatory properties.

The use of magnetic therapy contributes to the general relaxation of the body, and a decrease in excessive muscle tension. It accelerates and regulates peripheral blood circulation and accelerates metabolism, which is used in the healing procedures for slimming the body. Applying magnetic therapy after consulting with a specialist, you can improve your body.

Well known to the wide use of the magnetic field in everyday life, in production and in scientific research. It is enough to name the devices such as alternating current generators, electric motors, relays, elementary particle accelerators and various sensors. Consider in more detail what is the magnetic field and how it is formed.

What is a magnetic field - definition

The magnetic field is a power field acting on moving charged particles. The size of the magnetic field is grieved on the speed of its change. According to this feature, two types of magnetic field are distinguished: dynamic and gravitational.

The gravitational magnetic field occurs only near the elementary particles and is formed depending on the characteristics of their structure. Sources of dynamic magnetic field are moving electrical charges or charged bodies, conductor with current, as well as magnetized substances.

Properties of magnetic field

The great French scientist Andre Amper managed to find out the two fundamental properties of the magnetic field:

1. The main difference between the magnetic field from the electric and its basic property is that it is relative. If you take a charged body, leave it stationary in any reference system and place a magnetic arrow, then it will, as usual, point to the north. That is, it will not detect any field except the earth. If you start moving this charged body relative to the arrow, it will start rotating - this suggests that when the charged body moves, the magnetic field is also occurring other than electric. Thus, the magnetic field appears then and only if there is a moving charge.
2. The magnetic field acts on another electric current. So, you can detect it by tracing the movement of charged particles, - in the magnetic field they will deviate, the conductors with the current will move, the frame with the current to turn the magnetized substances to shift. Here you should remember the magnetic arrow of the compass, usually painted in blue colour- After all, it is just a piece of magnetized iron. It is always oriented to the north, because the earth has a magnetic field. Our entire planet is a huge magnet: there is a southern magnetic belt on the North Pole, and the Northern Magnetic Pole is located on the southern geographical pole.

In addition, the properties of the magnetic field include the following characteristics:

1. The power of the magnetic field is described by magnetic induction - this is a vector value that determines which force magnetic field affects moving charges.
2. The magnetic field may be permanent and alternating type. The first is generated by an electric field that does not change over time, the induction of such a field is also unchanged. The second most frequently generated by inductors feeding with alternating current.
3. The magnetic field cannot be perceived by human senses and is fixed only by special sensors.

Scientists from the National Laboratory of the High Magnetic Field (Maglab) at the University of Florida () created the world's most powerful superconducting magnet. The device with a diameter is not more centimeter and the size of no more roller for toilet paper (I do not know why, but the creators spend exactly such an analogy) can generate a record tension of the magnetic field of 45.5 Tesla. This is more than 20 times more powerful magnets of hospital apparatus magnetic resonance tomography. It is noted that only impulse magnets capable of maintaining a magnetic field for a fraction of a second, achieved higher intensity.

Everything in this universe moves and does not stand still. Rotate around the stars, the stars rotate around the galactic centers, and the galaxies themselves move in the intergalactic space. Some move alone, but gravity makes most galaxies form in groups called galactic clusters. The length of such galactic clusters can be tens of millions of light years. Due to this, the clusters are among the largest structures in the famous universe.