All formulas are taken in strict accordance with Federal Institute pedagogical measurements (FIPI)

3.3 MAGNETIC FIELD

3.3.1 Mechanical interaction of magnets

Near an electric charge, a peculiar form of matter is formed - an electric field. A similar form of matter exists around a magnet, but has a different nature of origin (after all, the ore is electrically neutral), it is called a magnetic field. To study magnetic field use straight or horseshoe magnets. Certain places on a magnet have the greatest attractive force; they are called poles (north and south). Opposite magnetic poles attract, and like magnetic poles repel.

Magnetic field. Magnetic induction vector

To characterize the strength of a magnetic field, use the magnetic field induction vector B. The magnetic field is graphically depicted using lines of force (magnetic induction lines). Lines are closed, have neither beginning nor end. The place from which magnetic lines emerge is the North Pole; magnetic lines enter the South Pole.

Magnetic induction B [Tl]- vector physical quantity, which is the strength characteristic of the magnetic field.

The principle of superposition of magnetic fields - if a magnetic field at a given point in space is created by several field sources, then magnetic induction is the vector sum of the inductions of each field separately :

Magnetic field lines. Pattern of field lines of strip and horseshoe permanent magnets

3.3.2 Oersted's experiment. Magnetic field of a current-carrying conductor. Picture of field lines of a long straight conductor and a closed ring conductor, a coil with current

A magnetic field exists not only around a magnet, but also around any current-carrying conductor. Oersted's experiment demonstrates the action electric current on a magnet. If a straight conductor carrying current is passed through a hole in a sheet of cardboard on which small iron or steel filings are scattered, then they form concentric circles, the center of which is located on the axis of the conductor. These circles represent the magnetic field lines of a current-carrying conductor.

3.3.3 Ampere force, its direction and magnitude:

Ampere power- the force acting on a current-carrying conductor in a magnetic field. The direction of Ampere's force is determined by the left-hand rule: if left hand positioned so that the perpendicular component of the magnetic induction vector B enters the palm, and the four extended fingers are directed in the direction of the current, then the thumb bent 90 degrees will show the direction of the force acting on the section of the conductor with the current, that is, the Ampere force.

Where I- current strength in the conductor;

B

L— length of the conductor located in the magnetic field;

α - the angle between the magnetic field vector and the direction of the current in the conductor.

3.3.4 Lorentz force, its direction and magnitude:

Since electric current represents the ordered movement of charges, the action of a magnetic field on a conductor with current is the result of its action on individual moving charges. The force exerted by a magnetic field on charges moving in it is called the Lorentz force. The Lorentz force is determined by the relation:

Where q— the magnitude of the moving charge;

V— module of its speed;

B— module of the magnetic field induction vector;

α is the angle between the charge velocity vector and the magnetic induction vector.

Please note that the Lorentz force is perpendicular to the speed and therefore it does not do work, does not change the modulus of the charge velocity and its kinetic energy. But the direction of speed changes continuously.

The Lorentz force is perpendicular to the vectors IN And v, and its direction is determined using the same left-hand rule as the direction of the Ampere force: if the left hand is positioned so that the component of magnetic induction IN, perpendicular to the speed of the charge, entered the palm, and four fingers were directed along the movement of the positive charge (against the movement of the negative charge, for example, an electron), then the thumb bent 90 degrees will show the direction of the Lorentz force acting on the charge Fl.

Motion of a charged particle in a uniform magnetic field

When a charged particle moves in a magnetic field, the Lorentz force does no work. Therefore, the magnitude of the velocity vector does not change when the particle moves. If a charged particle moves in a uniform magnetic field under the influence of the Lorentz force, and its speed lies in a plane perpendicular to the vector, then the particle will move in a circle of radius R.

Just as an electric charge at rest acts on another charge through electric field, an electric current acts on another current through magnetic field. The effect of a magnetic field on permanent magnets is reduced to its effect on charges moving in the atoms of a substance and creating microscopic circular currents.

The doctrine of electromagnetism based on two provisions:

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

Magnet interaction

Permanent magnet(or magnetic needle) is oriented along the Earth's magnetic meridian. The end that points north is called north pole(N), and the opposite end is south pole(S). Bringing two magnets closer to each other, we note that their like poles repel, and their unlike poles attract ( rice. 1 ).

If we separate the poles by cutting a permanent magnet into two parts, we will find that each of them will also have two poles, i.e. will be a permanent magnet ( rice. 2 ). Both poles - north and south - are inseparable from each other and have equal rights.

The magnetic field created by the Earth or permanent magnets is represented, like an electric field, by magnetic lines of force. A picture of the magnetic field lines of a magnet can be obtained by placing a sheet of paper over it, on which iron filings are sprinkled in an even layer. When exposed to a magnetic field, the sawdust becomes magnetized - each of them has north and south poles. The opposite poles tend to move closer to each other, but this is prevented by the friction of the sawdust on the paper. If you tap the paper with your finger, the friction will decrease and the filings will be attracted to each other, forming chains depicting magnetic field lines.

On rice. 3 shows the location of sawdust and small magnetic arrows in the field of a direct magnet, indicating the direction of the magnetic field lines. This direction is taken to be the direction of the north pole of the magnetic needle.

Oersted's experience. Magnetic field of current

IN early XIX V. Danish scientist Ørsted did important discovery, having discovered action of electric current on permanent magnets . He placed a long wire near a magnetic needle. When current was passed through the wire, the arrow rotated, trying to position itself perpendicular to it ( rice. 4 ). This could be explained by the emergence of a magnetic field around the conductor.

The magnetic field lines created by a straight conductor carrying current are concentric circles located in a plane perpendicular to it, with centers at the point through which the current passes ( rice. 5 ). The direction of the lines is determined by the right screw rule:

If the screw is rotated in the direction of the field lines, it will move in the direction of the current in the conductor .

The strength characteristic of the magnetic field is magnetic induction vector B . At each point it is directed tangentially to the field line. Electric field lines begin on positive charges and end on negative ones, and the force acting on the charge in this field is directed tangentially to the line at each point. Unlike the electric field, the magnetic field lines are closed, which is due to the absence of “magnetic charges” in nature.

The magnetic field of a current is fundamentally no different from the field created by a permanent magnet. In this sense, an analogue of a flat magnet is a long solenoid - a coil of wire, the length of which is significantly greater than its diameter. The diagram of the lines of the magnetic field created by him, shown in rice. 6 , is similar to that for a flat magnet ( rice. 3 ). The circles indicate the cross sections of the wire forming the solenoid winding. Currents flowing through the wire away from the observer are indicated by crosses, and currents in the opposite direction - towards the observer - are indicated by dots. The same designations are also accepted for magnetic field lines when they are perpendicular to the plane of the drawing ( rice. 7 a, b).

The direction of the current in the solenoid winding and the direction of the magnetic field lines inside it are also related 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 flowing in a clockwise direction creates a magnetic field in it, the direction of which coincides with the direction of movement of the right screw ( rice. 8 )

Based on this rule, it is easy to understand that the solenoid shown in rice. 6 , the north pole is its right end, and the south pole is its left.

The magnetic field inside the solenoid is uniform - the magnetic induction vector has a constant value there (B = const). In this respect, the solenoid is similar to a parallel-plate capacitor, within which a uniform electric field is created.

Force acting in a magnetic field on a current-carrying conductor

Experienced way It was found that a force acts on a current-carrying conductor in a magnetic field. In a uniform field, a straight conductor of length l, through which a current I flows, located perpendicular to the field vector B, experiences the force: F = I l B .

The direction of the force is determined left hand rule:

If the four outstretched fingers of the left hand are placed in the direction of the current in the conductor, and the palm is perpendicular to vector B, then the extended thumb will indicate the direction of the force acting on the conductor (rice. 9 ).

It should be noted that the force acting on a conductor with current in a magnetic field is not directed tangentially to its lines of force, like an electric force, but perpendicular to them. A conductor located along the lines of force is not affected by magnetic force.

Equation F = IlB lets give quantitative characteristics magnetic field induction.

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

Magnetic induction vector module B numerically equal to force, acting on a conductor of unit length located perpendicular to it, through which a current of one ampere flows.

In the SI system, the unit of magnetic field induction is the tesla (T):

Magnetic field. Tables, diagrams, formulas

(Interaction of magnets, Oersted's experiment, magnetic induction vector, vector direction, superposition principle. Graphic representation of magnetic fields, magnetic induction lines. Magnetic flux, energy characteristic of the field. Magnetic forces, Ampere force, Lorentz force. Movement of charged particles in a magnetic field. Magnetic properties of matter, Ampere's hypothesis)

Let's understand together what a magnetic field is. After all, many people live in this field all their lives and don’t even think about it. It's time to fix it!

Magnetic field

Magnetic field – special kind matter. It manifests itself in the action on moving electric charges and bodies that have their own magnetic moment (permanent magnets).

Important: the magnetic field does not affect stationary charges! A magnetic field is also created by moving electric charges, or by a time-varying electric field, or by the magnetic moments of electrons in atoms. That is, any wire through which current flows also becomes a magnet!

A body that has its own magnetic field.

A magnet has poles called north and south. The designations "north" and "south" are given for convenience only (like "plus" and "minus" in electricity).

The magnetic field is represented by magnetic power lines. The lines of force are continuous and closed, and their direction always coincides with the direction of action of the field forces. If metal shavings are scattered around a permanent magnet, the metal particles will show a clear picture of the magnetic field lines coming out of the north pole and entering the south pole. Graphic characteristic of a magnetic field - lines of force.

Characteristics of the magnetic field

The main characteristics of the magnetic field are magnetic induction, magnetic flux And magnetic permeability. But let's talk about everything in order.

Let us immediately note that all units of measurement are given in the system SI.

Magnetic induction B – vector physical quantity, which is the main force characteristic of the magnetic field. Denoted by the letter B . Unit of measurement of magnetic induction – Tesla (T).

Magnetic induction shows how strong the field is by determining the force it exerts on a charge. This force is called Lorentz force.

Here q - charge, v - its speed in a magnetic field, B - induction, F - Lorentz force with which the field acts on the charge.

F– a physical quantity equal to the product of magnetic induction by the area of ​​the circuit and the cosine between the induction vector and the normal to the plane of the circuit through which the flux passes. Magnetic flux is a scalar characteristic of a magnetic field.

We can say that magnetic flux characterizes the number of magnetic induction lines penetrating a unit area. Magnetic flux is measured in Weberach (Wb).

Magnetic permeability– coefficient that determines the magnetic properties of the medium. One of the parameters on which the magnetic induction of a field depends is magnetic permeability.

Our planet has been a huge magnet for several billion years. The induction of the Earth's magnetic field varies depending on the coordinates. At the equator it is approximately 3.1 times 10 to the minus fifth power of Tesla. In addition, there are magnetic anomalies where the value and direction of the field differ significantly from neighboring areas. Some of the largest magnetic anomalies on the planet - Kursk And Brazilian magnetic anomalies.

The origin of the Earth's magnetic field still remains a mystery to scientists. It is assumed that the source of the field is the liquid metal core of the Earth. The core is moving, which means the molten iron-nickel alloy is moving, and the movement of charged particles is the electric current that generates the magnetic field. The problem is that this theory ( geodynamo) does not explain how the field is kept stable.

The Earth is a huge magnetic dipole. The magnetic poles do not coincide with the geographic ones, although they are in close proximity. Moreover, the Earth's magnetic poles move. Their displacement has been recorded since 1885. For example, over the past hundred years the magnetic pole in Southern Hemisphere has shifted almost 900 kilometers and is now located in the Southern Ocean. The pole of the Arctic hemisphere is moving through the Arctic Ocean to the East Siberian magnetic anomaly; its movement speed (according to 2004 data) was about 60 kilometers per year. Now there is an acceleration of the movement of the poles - on average, the speed is growing by 3 kilometers per year.

What is the significance of the Earth's magnetic field for us? First of all, the Earth's magnetic field protects the planet from cosmic rays and solar wind. Charged particles from deep space do not fall directly to the ground, but are deflected by a giant magnet and move along its lines of force. Thus, all living things are protected from harmful radiation.

Several events have occurred over the course of Earth's history. inversions(changes) of magnetic poles. Pole inversion- this is when they change places. Last time this phenomenon occurred about 800 thousand years ago, and in total there were more than 400 geomagnetic inversions in the history of the Earth. Some scientists believe that, given the observed acceleration of the movement of the magnetic poles, the next pole inversion should be expected in the next couple of thousand years.

Fortunately, a pole change is not yet expected in our century. This means that you can think about pleasant things and enjoy life in the good old constant field of the Earth, having considered the basic properties and characteristics of the magnetic field. And so that you can do this, there are our authors, to whom you can confidently entrust some of the educational troubles with confidence! and other types of work you can order using the link.

On this lesson, the topic of which is: “Magnetic field of direct electric current”, we will learn what a magnet is, how it interacts with other magnets, write down the definitions of the magnetic field and the magnetic induction vector, and also use the gimlet rule to determine the direction of the magnetic induction vector.

Each of you has held a magnet in your hands and knows its amazing property: it interacts at a distance with another magnet or with a piece of iron. What is it about a magnet that gives it these amazing properties? Is it possible to make a magnet yourself? It is possible, and you will learn what is needed for this from our lesson. Let's get ahead of ourselves: if we take a simple iron nail, it will not have magnetic properties, but if we wrap it with wire and connect it to a battery, we will get a magnet (see Fig. 1).

Rice. 1. Nail wrapped with wire and connected to a battery

It turns out that to get a magnet, you need an electric current - the movement of an electric charge. The properties of permanent magnets, such as refrigerator magnets, are also associated with the movement of electric charge. A certain magnetic charge, like an electric one, does not exist in nature. It’s not needed, moving ones are enough electric charges.

Before exploring the magnetic field of a direct electric current, we need to agree on how to quantitatively describe the magnetic field. To describe magnetic phenomena quantitatively, it is necessary to introduce the force characteristic of the magnetic field. A vector quantity that quantitatively characterizes a magnetic field is called magnetic induction. It is usually designated as large Latin letter B, measured in teslas.

Magnetic induction is a vector quantity, which is a force characteristic of the magnetic field at a given point in space. The direction of the magnetic field is determined by analogy with the electrostatics model, in which the field is characterized by its action on a test charge at rest. Only here a magnetic needle (an oblong permanent magnet) is used as a “test element”. You saw such an arrow in a compass. The direction of the magnetic field at any point is taken to be the direction that the north pole N of the magnetic needle will indicate after reorientation (see Fig. 2).

A complete and clear picture of the magnetic field can be obtained by constructing the so-called magnetic field lines (see Fig. 3).

Rice. 3. Magnetic field lines of a permanent magnet

These are lines showing the direction of the magnetic induction vector (that is, the direction of the N pole of the magnetic needle) at each point in space. Using a magnetic needle, you can thus obtain a picture of the lines of force of various magnetic fields. Here, for example, is a picture of the magnetic field lines of a permanent magnet (see Fig. 4).

Rice. 4. Magnetic field lines of a permanent magnet

A magnetic field exists at every point, but we draw the lines at some distance from each other. This is simply a way to depict a magnetic field; we did the same with the electric field strength (see Fig. 5).

Rice. 5. Electric field strength lines

The more densely the lines are drawn, the greater the magnetic induction module in a given region of space. As you can see (see Fig. 4), the lines of force leave the north pole of the magnet and enter the south pole. Inside the magnet, the field lines also continue. Unlike electric field lines, which begin on positive charges and end on negative charges, magnetic field lines are closed (see Fig. 6).

Rice. 6. Magnetic field lines are closed

A field whose field lines are closed is called a vortex vector field. The electrostatic field is not a vortex, it is potential. The fundamental difference between vortex and potential fields is that the work of a potential field on any closed path is zero; for a vortex field this is not the case. The earth is also a huge magnet, it has a magnetic field that we detect with the help of a compass needle. More details about the Earth's magnetic field are described in the branch.

Our planet Earth is a large magnet, the poles of which are located near the intersection of the surface with the axis of rotation. Geographically, these are the South and North Poles. That is why the needle in the compass, which is also a magnet, interacts with the Earth. It is oriented in such a way that one end points to the North Pole and the other to the South Pole (see Fig. 7). Fig.7. The compass needle interacts with the Earth The one that points to the North Pole of the Earth was designated N, which means North - translated from English as “North”. And the one that points to the South Pole of the Earth is S, which means South - translated from English as “South”. Since opposite poles of magnets attract, the north pole of the arrow points to the South Magnetic Pole of the Earth (see Fig. 8). Rice. 8. Interaction of the compass and the magnetic poles of the Earth It turns out that the South Magnetic Pole is located at the North Geographic Pole. Conversely, the North Magnetic Pole is located at the South Geographic Pole of the Earth.

Now, having become acquainted with the magnetic field model, we will study the field of a conductor with direct current. Back in the 19th century, the Danish scientist Oersted discovered that a magnetic needle interacts with a conductor through which an electric current flows (see Fig. 9).

Rice. 9. Interaction of a magnetic needle with a conductor

Practice shows that in the magnetic field of a straight conductor carrying current, the magnetic needle at each point will be set tangent to a certain circle. The plane of this circle is perpendicular to the current-carrying conductor, and its center lies on the axis of the conductor (see Fig. 10).

Rice. 10. Location of the magnetic needle in the magnetic field of a straight conductor

If you change the direction of current flow through the conductor, then the magnetic needle at each point will turn in the opposite side(see Fig. 11).

Rice. 11. When changing the direction of flow of electric current

That is, the direction of the magnetic field depends on the direction of current flow through the conductor. This dependence can be described using a simple experimentally established method - gimlet rules:

if direction forward movement If the gimlet coincides with the direction of the current in the conductor, then the direction of rotation of its handle coincides with the direction of the magnetic field created by this conductor (see Fig. 12).

So, the magnetic field of a current-carrying conductor is directed at each point tangent to a circle lying in a plane perpendicular to the conductor. The center of the circle coincides with the axis of the conductor. The direction of the magnetic field vector at each point is related to the direction of the current in the conductor by the gimlet rule. Empirically, when changing the current strength and distance from the conductor, it has been established that the magnitude of the magnetic induction vector is proportional to the current and inversely proportional to the distance from the conductor. The modulus of the magnetic induction vector of the field created by an infinite conductor with current is equal to:

where is the proportionality coefficient, which is often found in magnetism. It is called the magnetic permeability of vacuum. Numerically equal to:

For magnetic fields, as for electric fields, the principle of superposition is valid. Magnetic fields created by different sources at one point in space add up (see Fig. 13).

Rice. 13. Magnetic fields from different sources add up

The total force characteristic of such a field will be vector sum strength characteristics of the fields of each source. The magnitude of the magnetic field induction, generated by current at a certain point, can be increased by bending the conductor into a circle. This will be clear if we consider the magnetic fields of small segments of such a turn of wire at a point located inside this turn. For example, in the center.

The segment marked , according to the gimlet rule, creates a field in it directed upward (see Fig. 14).

Rice. 14. Magnetic field of segments

The segment similarly creates a magnetic field at this point, directed there. Likewise for other segments. Then the total force characteristic (that is, the magnetic induction vector B) at this point will be a superposition of the force characteristics of the magnetic fields of all small segments at this point and will be directed upward (see Fig. 15).

Rice. 15. Total force characteristic at the center of the coil

For an arbitrary turn, not necessarily in the shape of a circle, for example for a square frame (see Fig. 16), the magnitude of the vector inside the turn will naturally depend on the shape, size of the turn and the current strength in it, but the direction of the magnetic induction vector will always be determined in the same way (as a superposition of fields created by small segments).

Rice. 16. Magnetic field of square frame segments

We have described in detail the determination of the direction of the field inside a coil, but in the general case it can be found much more simply, using a slightly modified gimlet rule:

if you rotate the handle of the gimlet in the direction in which the current flows in the coil, then the tip of the gimlet will indicate the direction of the magnetic induction vector inside the coil (see Fig. 17).

That is, now the rotation of the handle corresponds to the direction of the current, and the movement of the gimlet corresponds to the direction of the field. And not vice versa, as was the case with a direct conductor. If a long conductor through which current flows is rolled into a spring, then this device will consist of many turns. The magnetic fields of each turn of the coil will add up according to the principle of superposition. Thus, the field created by the coil at some point will be the sum of the fields created by each of the turns at that point. You can see the picture of the field lines of such a coil in Fig. 18.

Rice. 18. Coil power lines

Such a device is called a coil, solenoid or electromagnet. It is easy to see that the magnetic properties of the coil will be the same as those of a permanent magnet (see Fig. 19).

Rice. 19. Magnetic properties of the coil and permanent magnet

One side of the coil (which is in the picture above) acts as the north pole of the magnet, and the other side acts as the south pole. Such a device is widely used in technology because it can be controlled: it becomes a magnet only when the current in the coil is turned on. Note that the magnetic field lines inside the coil are almost parallel and their density is high. The field inside the solenoid is very strong and uniform. The field outside the coil is non-uniform; it is much weaker than the field inside and is directed in the opposite direction. The direction of the magnetic field inside the coil is determined by the gimlet rule as for the field inside one turn. For the direction of rotation of the handle, we take the direction of the current that flows through the coil, and the movement of the gimlet indicates the direction of the magnetic field inside it (see Fig. 20).

Rice. 20. Reel gimlet rule

If you place a current-carrying coil in a magnetic field, it will reorient itself, like a magnetic needle. The moment of force causing the turn is related to the magnitude of the magnetic induction vector at a given point, the area of ​​the coil and the current strength in it by the following relationship:

Now it becomes clear to us where the magnetic properties of a permanent magnet come from: an electron moving in an atom along a closed path is like a coil with current, and, like the coil, it has a magnetic field. And, as we saw with the example of a coil, many turns with current, ordered in a certain way, have a strong magnetic field.

The field created by permanent magnets is the result of the movement of charges inside them. And these charges are electrons in atoms (see Fig. 21). Rice. 21. Movement of electrons in atoms Let us explain the mechanism of its occurrence at a qualitative level. As you know, electrons in an atom are in motion. So, each electron in each atom creates its own magnetic field, thus creating a huge number of magnets the size of an atom. For most substances, these magnets and their magnetic fields are randomly oriented. Therefore, the total magnetic field created by the body is zero. But there are substances in which the magnetic fields created by individual electrons are oriented in the same way (see Fig. 22). Rice. 22. Magnetic fields are oriented in the same way Therefore, the magnetic fields created by each electron add up. As a result, a body made of such a substance has a magnetic field and is a permanent magnet. In an external magnetic field, individual atoms or groups of atoms, which, as we have found out, have their own magnetic field, turn like a compass needle (see Fig. 23). Rice. 23. Rotation of atoms in an external magnetic field If they were not previously oriented in one direction and did not form a strong total magnetic field, then after the elementary magnets are ordered, their magnetic fields will add up. And if after the action of an external field the order is preserved, the substance will remain a magnet. The described process is called magnetization.

Designate the poles of the current source supplying the solenoid at the voltage shown in Fig. 24 interaction. Let's think: a solenoid in which a direct current flows behaves like a magnet.

Rice. 24. Current source

According to Fig. 24 it can be seen that the magnetic needle is oriented with its south pole towards the solenoid. Like poles of magnets repel each other, and opposite poles attract. It follows that the left pole of the solenoid itself is north (see Fig. 25).

Rice. 25. Left pole of the solenoid is north

Magnetic induction lines leave the north pole and enter the south pole. This means that the field inside the solenoid is directed to the left (see Fig. 26).

Rice. 26. The field inside the solenoid is directed to the left

Well, the direction of the field inside the solenoid is determined by the gimlet rule. We know that the field is directed to the left - so let's imagine that the gimlet is screwed in this direction. Then its handle will indicate the direction of current in the solenoid - from right to left (see Fig. 27).

The direction of the current is determined by the direction in which the positive charge moves. And a positive charge moves from a point with a higher potential (positive pole of the source) to a point with a lower potential (negative pole of the source). Consequently, the source pole located on the right is positive, and on the left is negative (see Fig. 28).

Rice. 28. Determination of source poles

Problem 2

A frame with an area of ​​400 is placed in a uniform magnetic field with an induction of 0.1 T so that the normal of the frame is perpendicular to the induction lines. At what current strength will torque 20 act on the frame (see Fig. 29)?

Rice. 29. Drawing for problem 2

Let us reason: the moment of force causing the turn is related to the magnitude of the magnetic induction vector at a given point, the area of ​​the coil and the current strength in it by the following relationship:

In our case, all the necessary data is available. It remains to express the required current strength and calculate the answer:

The problem is solved.

References

1. Sokolovich Yu.A., Bogdanova G.S. Physics: A reference book with examples of problem solving. - 2nd edition repartition. - X.: Vesta: Ranok Publishing House, 2005. - 464 p.
2. Myakishev G.Ya. Physics: Textbook. for 11th grade general education institutions. - M.: Education, 2010.

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Homework

“Determination of the magnetic field” - Using the data obtained during the experiments, fill out the table. J. Vern. When we bring a magnet to a magnetic needle, it turns. Graphic representation of magnetic fields. Hans Christian Oersted. Electric field. A magnet has two poles: north and south. The stage of generalization and systematization of knowledge.

“Magnetic field and its graphical representation” - Inhomogeneous magnetic field. Current coils. Magnetic lines. Ampere's hypothesis. Inside a strip magnet. Opposite magnetic poles. Polar lights. Magnetic field of a permanent magnet. Magnetic field. Earth's magnetic field. Magnetic poles. Biometrology. Concentric circles. Uniform magnetic field.

“Magnetic field energy” is a scalar quantity. Calculation of inductance. Constant magnetic fields. Time for relaxation. Definition of inductance. Coil energy. Extracurrents in a circuit with inductance. Transient processes. Energy density. Electrodynamics. Oscillatory circuit. Pulsed magnetic field. Self-induction. Magnetic field energy density.

“Characteristics of the magnetic field” - Magnetic induction lines. Gimlet's rule. Rotate along the lines of force. Computer model of the Earth's magnetic field. Magnetic constant. Magnetic induction. Number of charge carriers. Three ways to set the magnetic induction vector. Magnetic field of electric current. Physicist William Gilbert.

“Properties of a magnetic field” - Type of substance. Magnetic induction of magnetic field. Magnetic induction. Permanent magnet. Some values ​​of magnetic induction. Magnetic needle. Speaker. Magnetic induction vector module. Magnetic induction lines are always closed. Interaction of currents. Torque. Magnetic properties of matter.

“Movement of particles in a magnetic field” - Spectrograph. Manifestation of the Lorentz force. Lorentz force. Cyclotron. Determination of the magnitude of the Lorentz force. Security questions. Directions of Lorentz force. Interstellar matter. The task of the experiment. Changing parameters. Magnetic field. Mass spectrograph. Movement of particles in a magnetic field. Cathode ray tube.

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