Why do permanent magnets need an electric current to maintain their magnetic field

Permanent magnets are now basically divided into two materials, one is ferrite.

One is NdFeB, and the finished magnet is not magnetic at first, that is, the magnetic domain inside the magnet.

It is messily arranged, when a large magnetic field is added to the magnet, the magnetic domain inside the magnetic steel will be rearranged along the direction of the external magnetic field, if the external magnetic field is large enough, then the magnetic domain inside the magnetic steel will be completely in one direction, and when the external magnetic field disappears, the direction of the magnetic domain inside the magnetic steel will not change, which is called magnetization. Therefore, the magnetized magnet does not need to be magnetic under the condition of an external magnetic field.

Magnet coercivity of NdFeB.

Larger, that is, in order for the magnetized magnet to disappear its magnetism, a large reverse magnetic field must be added.

We know that an atom is made up of a positively charged nucleus and negatively charged electrons revolving around the nucleus. Electrons not only revolve around the nucleus, but also spin, and these movements of electrons in microscopic particles such as atoms and molecules form a "molecular circulation". In the interior of a permanent magnet, such a molecular circulation is arranged in one direction, and the n and s poles will be shown on the macroscopic level, that is, they have magnetism.

So it doesn't require an applied current to maintain the magnetic field.

Because the permanent magnet has been "magnetized", forming a permanent magnetism. (Permanent magnets are made of "hard magnetic materials", and "magnetization" means "the regular arrangement of molecular magnetic domains").

The first floor and the third floor are macroscopic, but there are no specific details, the second floor is good, in fact, you can understand it when you study university physics ********************=== The following is a more detailed explanation.

Reasons why it can't be achieved:

In the process of using your energy, it will always be dissipated in various forms into thermal energy, and the heat energy itself cannot do work, and the heat difference can be.

Whether the magnet perpetual motion machine can be realized mainly depends on the utilization rate of the magnetic energy of the permanent magnet in the permanent magnet motor. From the point of view of electric excitation motor to permanent magnet motor, the efficiency of permanent magnet motor is about 10% higher than that of electric magnet motor, from this point of view, in the electric excitation motor, the power consumption of the excitation winding accounts for 10 of the total power of the motor, and the magnetic energy provided by the permanent magnet in the permanent magnet motor also accounts for 10% of the total power of the motor.

It can be seen that in the permanent magnet motor, the energy provided by the permanent magnet is very small compared with the input energy of the motor, if this proportion is increased to 30% or 50%, then the efficiency of the motor can reach 100% or higher.

It's kind of incredible. According to the law of conservation of energy, energy cannot be created in a vacuum. But permanent magnets should be an exception. Although this magnetic energy is not very large, if it is used well, it is still possible to compensate for the internal loss of the motor and increase a certain output in the motor.

To summarize as follows: in fact, any theorem and law has its scope of application, there are four basic forces in nature, the law of conservation of energy only applies to electromagnetic force, to the range of weak force to use the law of conservation of mass and energy, only the conversion of mass into energy can use the law of conservation of energy.

According to the law of conservation of energy, if there is a force, work can be done, and energy must be consumed, and what energy maintains the existence of strong force and gravitational force, which can require huge energy, should not be explained by the law of conservation of energy.

The so-called magnetic field refers to the space where there is a magnetic force. The magnetic field is one of the basic forms of existence of matter, and it exists in the space around the magnet, the space around the moving charge, and the space around the electric current. The most common phenomenon in magnetic fields is the mutual attraction or repulsion of two magnetic objects, so the interaction between magnets is carried out by magnetic fields.

The magnetic field will also produce a force on the energized conductor, indicating that the magnetic field has the nature of force, and when the energized conductor moves within the magnetic field, the magnetic field force will do work on the energized conductor, indicating that the magnetic field has energy. These manifestations illustrate the materiality of the magnetic field.

The magnetic field is generated by a moving charge or electric current. The magnetic field generated by the permanent magnet is also due to the existence of molecular current inside the permanent magnet, which refers to the circulating current corresponding to the total magnetic effect on the outside world in the whole molecule. If the current is constant, the magnetic field is also constant, and the constant magnetic field is called a constant magnetic field or a static magnetic field.

According to the book, the electrons inside the metal or metal oxide move irregularly, and the magnetic field generated cancels each other out, and there is no magnetism, and there are many electrons inside the magnet that move according to a certain law, so there is magnetism.

The specific arrangement of the internal structure leads to the creation of a specific movement of electric charges.

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The force of the core of the electromagnet in the ammeter and the residual macro of the permanent magnet needs to be considered. In ammeters, both electromagnets and permanent magnets play an important role. <>

The electromagnet generates a magnetic field by applying electricity, which causes the magnetic field around the core to change, which causes the force to move the ammeter pointer to the corresponding position and display the magnitude of the current. When the current passes through the electromagnet, the magnetic field of the permanent magnet and the magnetic field of the electromagnet interact to produce a slip moment, so that the ammeter pointer stays stably in the corresponding position. <>

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Summary. The force of the electromagnet core and the permanent magnet in the ammeter needs to be taken into account. In an ammeter, the current passes through a coil with an iron core around this coil, and when the current passes through the coil, a magnetic field is generated, and this magnetic field causes the magnetic material in the iron core to be magnetized, thus creating a magnetic force that will make the pointer move.

Similarly, permanent magnets generate a magnetic field that interacts with the magnetic field generated by the coil to create a force that also moves the pointer. Therefore, when designing an ammeter, the force of the electromagnet's core and permanent magnet needs to be considered to ensure the sensitivity and accuracy of the pointer. At the same time, factors such as the number of turns of the coil, the magnitude of the current, and the material of the core need to be considered to ensure the performance and accuracy of the ammeter.

Hello dear! We'll be happy to answer this question for you. Is it necessary to consider the force of the core of the electromagnet and the permanent magnet in the ammeter?

Pro, is there a need to consider the force of the electromagnet core and the permanent magnet in the ammeter: Yes, it needs to be considered.

The force of the electromagnet core and the permanent magnet in the ammeter needs to be taken into account. In an ammeter, the current passes through a coil with an iron core around this coil, and when the current passes through the coil, a magnetic field is generated, and this magnetic field causes the magnetic material in the iron core to be magnetized, thus creating a magnetic force that will make the pointer move. Similarly, permanent magnets generate a magnetic field that interacts with the magnetic field generated by the coil to create a force that also moves the pointer.

Therefore, when designing an ammeter, it is necessary to consider the force of the electromagnet's core and permanent magnet to ensure the sensitivity and accuracy of the pointer. At the same time, it is also necessary to consider the number of turns of the coil, the current size and the material of the iron core to ensure the performance and accuracy of the ammeter.

According to Faraday's theory, the atoms that make up matter are magnetic, because electrons surround the atoms.

The nuclear motion capacitance excites the magnetic field; If the atoms inside the substance are arranged in such a way that their magnetism cancels each other out, then the substance does not exhibit magnetism; The opposite is the performance.

The arrangement of atoms in magnetic materials is regular, and experiments have shown that high temperatures and strong vibrations can disrupt this arrangement.

Therefore, theoretically, the magnetism of a permanent magnet can be eliminated.

There's no indication that the magnetism of natural magnets in nature is slowly diminishing, for example, the first magnet that humans touched is still the same – if we know it's the magnet.

Yes, though, the magnetic force will gradually weaken over time.

It's just a little bit longer, but not really forever.