Is there also a magnetic field inside the magnet Is it true that there is a magnetic field around th

I suspect that there is a paradox here, and that most sophomores in high school will do such a classic problem after learning Lenz's law:

As shown in Figure 1, there is a circular conductor rod under the bar magnet, and the bar magnet moves downward (does not reach the plane where the circular conductor rod is located), does the circular conductor rod have a tendency to shrink or expand?

You may think it's simple.

The bar magnet moves downward, although the round conductor rod tends to shrink.

Of course, all the references say the same.

However, there is a problem: the magnetic inductance line is like this at this time, but I extended the magnetic inductance line as shown in Figure 3, the position of the bar magnet and the ring did not change, but the magnetic inductance line was extended, and there was a magnetic field line that penetrated and then pierced out.

That's what I'm trying to say, according to the magnetic field lines at this time, the downward movement of the bar magnet and the circular conductor rod have a tendency to expand. This leads to the question of what exactly the magnetic inductance lines look like.

In fact, although this is the case in the textbook, as shown in Figure 4, according to the saying that the magnetic inductance line is circular, the porcelain inductance line at the beginning is to turn back, so what does this magnetic inductance line look like? It's not so easy to draw! There are two ways to draw, one answer for one part, and another answer for the whole picture, and the two answers are contradictory ......Hehe, that's cool, isn't it?

But there is only one fact, obviously there is a problem here, what the magnetic inductance line looks like, must be determined by something, in other words, the change in the strength of the magnetic field, will lead to the change in the density of the magnetic inductance line, or the change in the shape of the magnetic inductance line, or ......... change in the shape of the magnetic inductance lineFigure in.

Of course there is, because the magnetic lines are closed.

Right. Because the magnetic field lines are closed lines.

Right. It's just that the direction of the magnetic field is opposite to the outside of the magnet.

Summary. The magnetic field is a special substance that cannot be seen and touched. There is a magnetic field around the magnet, and the interaction between the magnets is mediated by the magnetic field.

Hello, I am Mr. Xiaoxiao, and I am happy to serve you and answer your questions!

Right. The magnetic field is a special substance that cannot be seen and touched. There is a magnetic field around the magnet, and the interaction between the magnets is mediated by the magnetic field.

Simple definition: A substance that has a magnetic effect on a small magnetic needle placed in it is called a magnetic field.

Hello, the above is my answer to this question, do you still have any questions?

There must be. The basic property of a magnetic field is the ability to exert a magnetic force on the magnet placed in it.

Test Center Name: Magnetic Phenomena.

Magnetic phenomenon: 1. Magnetism: The object has the property of attracting ferrous objects, which is called magnetism.

2. Magnets: Objects with magnetic properties are called magnets.

Permanent magnets are objects that are able to maintain their magnetic properties for a long time. The main component of natural magnet is Fe3O4, whose magnetic properties can be maintained for a long time, but the magnetic properties are weak, and artificial magnets are obtained by magnetization of hard magnetic materials.

3. Magnetic pole: The magnetic strength of each part of the magnet is different, and the area with the strongest magnetism is called the magnetic pole.

The magnetic pole of the guide that can rotate freely when it is stationary is called the south pole, also known as the S pole; The magnetic pole pointing north is called the North Pole, also known as the N-pole.

4. The law of interaction between magnetic poles: the repulsion force between the poles of the same name is the gravitational force.

Regarding the magnetic field, the following statement is true ( ).

a The magnetic field must have a strong effect on the magnet placed in it

b The magnetic field must have a strong effect on the current put into it.

c The magnetic field must have a strong effect on the moving charge placed in it.

d Magnetic inductance lines are practically non-existent, so it is impossible to simulate magnetic inductance lines.

Answer Analysis:a. The magnetic field must have a magnetic force effect on the magnet placed in it, so A is correct;

b. The magnetic field does not necessarily have the effect of magnetic field force on the current put into it, and when it is parallel to the magnetic field, there must be no magnetic field force; When perpendicular to the magnetic field, the magnetic field force is the largest, so b is wrong;

c. The magnetic field does not necessarily have a strong effect on the moving charge placed in it, and when the direction of motion is parallel to the direction of the magnetic field, there is no magnetic field force, so c is wrong;

d. The magnetic inductance line actually does not exist, so the thin iron filings can be used to reflect the density of the magnetic inductance line, so D is wrong;

Therefore, a

The energized coil rotates in a magnetic field, which is caused by the interaction of magnetic fields. The charged coil generates a magnetic guessing field, which acts with the magnetic field of the magnet, so the motor can rotate.

When the electromagnet is energized, it will produce N and S poles, and these two poles will exert force with the magnet: the same poles will repel each other, and the different poles will attract. In this way, the electromagnet on the shaft will rotate, and when the equilibrium point is reached, the two will act in the opposite direction, so that the electromagnet can rotate again and again.

A brief introduction to other facts about magnetic fields.

There is a magnetic field around the magnet, and the interaction between the magnets is mediated by the magnetic field, so the two magnets can work without physical contact. An electric current, a moving charge, a magnet, or a special form of matter that exists in the space around the changing electric field. Since the magnetism of a magnet is the same as the current, the current is the movement of an electric charge, so in a nutshell, the magnetic field is generated by the change of the moving charge or electric field.

The real source of the field where the moving charge produces the magnetic field is the magnetic field produced by the moving electrons or moving protons. For example, the magnetic field generated by an electric current is the magnetic field generated by electrons moving in a wire.

** to the movement of electric charges.

According to Ampère, the essence of magnetism should be attributed to the magnetic effect of electric current, that is, all magnetic phenomena originate from the movement of electric currents or charges. The molecules of any substance have molecular currents, which are equivalent to a primordial magnet, the chaotic arrangement of molecular currents makes the whole object non-magnetic, and the regular arrangement of molecular currents makes the object show magnetism. Ampere's hypothesis is confirmed by modern physics

The magnetic properties of atoms and molecules are produced due to the rapid spinning of electrons around the nucleus or around their own axis.

The magnetic domain theory uses quantum theory to explain the magnetization mechanism of ferromagnetics from a microscopic level. The so-called magnetic domain refers to a small area inside the magnetic material, each region contains a large number of atoms, and the magnetic moments of these atoms are neatly arranged like small magnets, but the direction of the atomic magnetic moment arrangement is different between adjacent regions, as shown in the figure. The interface between the individual domains is called the domain wall.

Macroscopic objects generally always have many magnetic domains, so that the direction of the magnetic moment of the magnetic domains is different, and the results cancel each other out, the vector sum is zero, and the magnetic moment of the whole object is zero, and it cannot attract other magnetic materials. In other words, magnetic materials do not show magnetism externally under normal circumstances. It is only when a magnetic material is magnetized that it can show its magnetic properties to the outside world.