The current is forced in a magnetic field, why does the electric current produce a magnetic field

The conclusion of the first problem is that the toroidal current is subjected to a force that is reversed to the center of the circle everywhere, which is equivalent to an expanding force.

Think of it as a small magnetic needle and the conclusion is the same. And you feel incomprehensible because we have a conclusion that we have by default as correct: the small magnetic needle placed on a uniform magnetic field force, is subjected to a flat force, i.e. it is attracted or repulsed.

Actually, it's wrong! The small magnetic needle is not subject to the flat force, but only the moment of rotation! The opposite-sex attraction of magnets we usually see is actually the result of non-uniform magnetic fields. The closer you are to the pole of the magnet, the greater the strength of the magnetic field.

The overall force of the coil can also be analyzed without being divided into current elements. It is analyzed by the force of the magnetic moment in the magnetic field. The current circle can be seen as only a magnetic moment, m=ia, ignoring the direction (it is difficult to type), i is the current, and a is the area of the ring.

In the magnetic field, only the moment is applied, l=m x b, in the middle is the vector multiplication, and b is the strength of the magnetic field. It can be seen that the magnetic field gives only one torsional force to the magnetic moment, which is parallel to the direction of the magnetic field. This force is maximum when the direction of the magnetic moment and the direction of the magnetic field are perpendicular to it.

In addition, a flattening force is applied to a non-uniform magnetic field. Check it yourself, it's all symbols, it's not easy to write.

The questions you add later are understood in terms of Lenz's law. When the magnetic field suddenly increases, the direction of movement of the wire frame will inevitably eventually cause the magnetic field in the frame to decrease. That is, there is a tendency to move out of the magnetic field.

Is it similar? 1. The magnetic field of the magnet is not a uniform magnetic field, and there are transverse components in addition to longitudinal components.

2. It is easy to determine by using the Lenz theorem that the magnetic force will keep the coil away from the magnetic field.

According to Maxwell's theory, an electric current generates a magnetic field. From Maxwell's equations, it can be deduced that electromagnetic waves propagate at the speed of light in a vacuum, and then make the conjecture that light is electromagnetic waves. Maxwell's equations and Lorentz force equations are fundamental equations for classical electromagnetism.

From the relevant theories of these basic equations, modern power technology and electronic technology have been developed.

PrincipleSince classical physics does not use the concept of elementary particles to study magnetic fields, electromagnetism and electrodynamics define the cause of magnetic fields as the directional motion of point charges, and explain the origin of magnets as magnetic domains. Modern physics shows that the ultimate structural composition of any matter is electrons (with a unit negative charge), protons (with a unit positive charge), and neutrons (externally showing electrical neutrality).

A point charge is a point of matter that contains excess electrons (with a unit negative charge) or protons (with a unit positive charge), so the cause of the magnetic field generated by the current can only be attributed to the magnetic field produced by the moving electrons.

Reason: According to Maxwell's equations, a changing electric field produces a magnetic field. Motion is a change, so the electric field of motion produces a magnetic field.

There is an electric field in the space around the charge, and the motion of the charge causes the electric field to move, so the moving charge produces a magnetic field. Electric current is the flow of electric charges, so the electric current creates a magnetic field. A constant magnetic field is generated around a constant current.

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. From the point of view of modern physics, the only ultimate components of matter that can form an electric charge are electrons (with a unit negative charge) and protons (with a unit of positive charge).

The force exerted by a magnetic field on an electric current is often referred to as the ampere force, which commemorates the outstanding contribution of the French physicist Ampère to the study of the force exerted by magnetic fields on electric currents.

The force exerted on an energized wire in a magnetic field. A straight wire with current I and length L. The ampere force experienced in a uniform magnetic field b is:

f=ilbsin, where is (i,b), is the angle between the direction of the current and the direction of the magnetic field.

When the conductor rod cuts the magnetic inductance line, the ampere force (essentially the Lorentz force) causes the free charge in the conductor rod to move directionally, causing the potential difference (electromotive force) between the two ends of the conductor rod, and the existence of the potential difference makes the charge have potential energy, that is, electric energy.

In this way, the ampere force does negative work to convert mechanical energy into electrical energy. When the charge moves directionally, an electric current is formed, and the current is acted on in the magnetic field by the ampere force, which does negative work.

Ampere force work, we have to combine the micro explanation of ampere force to explain:

Ampere force is not a simple force as a magnetic field force, it is the resultant force of the magnetic field force and other forces acting in a conductor. Other elements here include the electric field force as well as the inelastic scattering interaction force.

These forces are to do work on the electrons and atoms, which causes the magnetic field to cut the energized conductor moving from the magnetic inductance lines to be destined to move at variable speed (unless an external force counteracts the ampere force). From this, we can conclude that the work done by ampere force is not consuming the magnetic field energy, but consuming the electrical energy of the conductor and turning the electrical energy into the kinetic energy of the conductor.

It can be determined by the right-hand rule:Stretch out your right hand, so that the thumb is perpendicular to the other four fingers, and all are in the same plane as the palm, put the right hand into the magnetic field, let the magnetic field lines perpendicular to the palm of the hand, and the thumb points to the direction of the conductor's movement, then the direction of the other four fingers is the direction of the induced current.

Magnetogeneous electricity was discovered by Faraday. Principle: When a part of the conductor of a closed circuit is cut into magnetic inductance lines, the phenomenon that an electric current will be generated on the conductor is called electromagnetic induction, and the current generated is called induced current.

Discovery process. In 1831, Faraday, a master of electricity, discovered that magnetism can generate electricity. He found two copper wires about 62 meters long and a thick wooden stick, and wound the two copper wires around the wooden sticks, and the two ends of the copper wires were connected to the galvanometer power supply.

Then he closed the power switch, and at this time, he seemed to feel the needle of the ammeter jump, and then pointed back to 0 point, could it be that the induced current was generated at the moment of the switch.

Faraday pulled the switch off and was about to reassemble to look again, and when the switch was pulled open, he saw the pointer bounce again, and then return to 0 o'clock. Wooki: He repeatedly pulled the switch open and closed, and found the same result.

Based on this experiment, Faraday summarized the law of electromagnetic induction: when the magnetic flux passing through the induction loop changes, an induced current will be generated in the loop, and the direction of the induced current always hinders the change of the magnetic flux in the loop, and the magnitude is proportional to the change in the magnetic flux per unit of time.

Negatively charged, electrons flow in the opposite direction to a conventional current within the metal.

Current in a magnetic field A closed coil cuts the magnetic inductance lines to form an electric current.

: The magnetic effect of electric current (electricity produces magnetism): Oster discovered that any wire with electric current can produce an endogenous magnetic field around it, which is called the magnetic effect of electric current.

The magnetic field generated around a long straight wire with an electric current passing through it. A magnetic field is generated around a long straight wire that is current-flowing, and the shape of the magnetic inductance line is a concentric circle closed with the wire as the center, and the direction of the magnetic field is perpendicular to the direction of the current.

The magnetic field of an electric current, the Oersted experiment and its magnetic field of an energized solenoid.

There is a saying that a changing magnetic field can produce an electric field, and a changing electric field can produce a magnetic field. The current must be a magnetic field, but the magnetic field does not necessarily produce the current, you have to have conductors and circuits.

The force exerted on an energized wire in a magnetic field is called ampere force. It was first experimentally determined by the French physicist A. Ampère. It can be expressed as:

If a straight wire with a current intensity of i and a length l is placed in a uniform external magnetic field with a magnetic induction intensity of b, the ampere force on the wire is f=iblsin, where is the angle between the current direction in the wire and the b direction, and the units of f, l, i and b are n, m, a and t, respectively. The direction of the ampere force is perpendicular to the plane determined by the energized wire and the direction of the magnetic field, and the direction between i, b, and f is determined by the left-hand rule. The ampere force exerted on an arbitrarily shaped wire in a uniform magnetic field can be seen as the vector sum of the ampere force experienced by an infinite number of linear current elements iδl in a magnetic field.

The significance of the ampere force is that, on the one hand, it further points out the interconnection between electricity and magnetism; On the other hand, the application value, the working principle of the electric motor is based on ampere force.

The essence of ampere force work: it plays the role of transferring energy, transferring the energy of the power supply to the energized straight wire, and the magnetic field itself cannot provide energy, and the characteristics of ampere force work are similar to static friction work.

The force exerted by the magnetic field on the electric current is known as the Lorentz force.

It is a force exerted by moving charged particles in an external magnetic field. When charged particles move, they produce a magnetic field, and the magnetic field in the outer magnetic field interacts with the magnetic field of the moving charged particles, creating an acting force. The direction of this force is perpendicular to the direction of the velocity of the moving charged particle and the direction of the external magnetic field, and the magnitude is related to the amount of charge and velocity of the moving charged particle and the strength of the external magnetic field.

The Lorentz force is an important concept in electromagnetism that describes the action of an electric current on a magnetic field and the action of a magnetic field on an electric current. In many cases, we can ** the way the current moves according to the magnitude and direction of the Lorentz force. For example, in an electric motor, the Lorentz force on an electric current in an external magnetic field causes the motor to rotate, thus converting electrical energy into mechanical energy.

The Lorentz force is also closely related to other physical phenomena, such as the Hall effect. The Hall effect is an electromagnetic phenomenon that describes the difference between the electric field and electric potential produced by an electric current moving in an external magnetic field. This phenomenon is widely used in booth sensors and magnetic field measuring instruments.

In conclusion, the Lorentz force is an important concept in electromagnetism that describes the force experienced by an electric current in an external magnetic field and the force produced by an electric current acting on an external magnetic field. In the study of electromagnetic phenomena and applications, it is very important to correctly understand and apply the Lorentz force.

The importance of the force of the magnetic field on the electric current

1. Understand the behavior of current in electrical equipment: in electrical equipment such as motors, electromagnetic Huai Xun iron, electric furnaces, generators, etc., the interaction between the current and the external magnetic field in the circuit is involved, and the force of the magnetic field on the current is an important theoretical basis for explaining this phenomenon.

2. Study of electromagnetic phenomena: For example, the study of electromagnetic waves, electromagnetic induction, electromagnets, Hall effect and other phenomena are inseparable from the theoretical basis of the force of magnetic field on electricity and flow.

3. Used in technical fields: motors, generators, electromagnets, sensors and other equipment made of magnetic fields are widely used in electrical, energy, transportation, communications, medical and many other fields.

4. Promote the development of science: The force of magnetic field on electric current is an important part of electrodynamics and electromagnetic field theory, and plays an important role in promoting the development of science.