There is amperage, how to judge the direction of the current

The rule of the right hand is that the right hand is flattened so that the thumb is perpendicular to the other four fingers and is in the same plane as the palm. Put the right hand into the magnetic field, if the magnetic inductance line is perpendicular to the palm of the hand (when the magnetic inductance line is a straight line, it is equivalent to the palm facing the n pole), and the thumb points to the direction of the wire movement, then the direction of the four fingers is the direction of the induced current (induced electromotive force) in the wire.

Generally know any two of the magnetic field, the direction of the current, and the direction of motion, allowing you to judge the third direction.

Right-handed spiral rule: Hold the solenoid with your right hand. Bend your four fingers in the direction of the solenoid's current, and the end of your thumb is the north pole of the energized solenoid.

For the magnetic field of a straight current, the thumb points in the direction of the current, and the other four fingers are bent in the direction of the magnetic inductance line (the direction of the magnetic field or the direction of the north pole of the small magnetic needle or the direction of force on the small magnetic needle).

Knowing the direction of the ampere force is knowing the direction of movement. The direction of the current can be judged using the above method.

The left-hand rule is used to determine the direction of the ampere force on the current element in the magnetic field.

Stretch out your left hand so that the thumb and finger are in the same plane and perpendicular, let the magnetic field pass through the palm, and the four fingers point in the direction of the current, then the direction of the thumb is the direction of ampere.

It is important to note that if the direction of the current is not perpendicular to the direction of the magnetic field, let the magnetic field pass diagonally through the palm. In addition, pay attention to the judgment of the direction of the current, the direction of the positive charge is the current direction, and the negative charge is the opposite direction of the current.

According to Ampere's rule.

Hold the solenoid with your right hand so that your thumb indicates the n pole of the energized solenoid, then the direction in which the four fingers are bent is the direction of the current.

The positive and negative poles of the power supply can be judged according to the direction of the current, if the current flows from the left end of the solenoid, that is, the left end of the power supply is the positive pole, and the right end is the negative pole.

Assuming that the energized wire is held with the right hand and the thumb is pointing in the direction of the current, then the four fingers bent represent the direction of the magnetic field around the wire. Suppose you hold an energized solenoid with your right hand and your four fingers bent in the direction of the current, then the thumb pointing is the direction of the magnetic field inside the energized solenoid.

Ampere's rule is mainly applied to:

1. The current carried by the solenoid will produce a magnetic field. Use the right-handed spiral rule.

The direction of the magnetic field can be determined. Hold the solenoid with your right hand, point four fingers in the direction of the current, and then extend your thumb along the central axis of the solenoid, then the direction of the magnetic field is the direction of the thumb.

2. The right-hand spiral rule can also be used to identify the direction of the magnetic field around a wire. For this usage, the right-hand spiral rule is called the "ampere's right-hand spiral rule", or "ampere's rule". If you point the thumb of your right hand in the direction of the current of the wire, and then hold the other four fingers in the direction of the wire, the direction in which the four fingers are bent is the direction of the magnetic field.

The judgment of the ampere force is the current in the original circuit;

Of course, the current in the original circuit can be an induced current generated by the change of magnetic flux, and the direction of the original magnetic field is not induced, but only the direction of the original magnetic field.

Lenz's law is generally a qualitative analysis problem that solves the choice-fill-in-the-blank.

安培力 [ān péi lì].

The force exerted on an energized wire in a magnetic field.

Popular Science China |This entry is reviewed by the "Science Popularization China" Science Encyclopedia Entry Compilation and Application Work Project.

Ampere (Ampere's force) is the force exerted on an energized wire in a magnetic field. It was first experimentally determined by the French physicist A. Ampère. It can be expressed as:

If a straight wire with a length of l with current intensity i is placed in a uniform external magnetic field with a magnetic induction intensity of b, the ampere force experienced by 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, and 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 pin exerted by an infinite number of linear current elements iδl in a magnetic field [1].

In the special theory of relativity, there is a certain connection between the ampere force and the Lorentz force of charged particles.

Use the left-hand rule to determine the direction of the ampere force: let the magnetic wire pass through the palm of the hand, and point the four fingers in the direction of the current, and the direction of the thumb is the direction of the ampere force on the energized wire in the magnetic field.

The specific steps are as follows:

Extend your left hand so that your thumb is in the same plane as the other fingers.

Let the magnetic lines pass through the palm of the hand, that is, the palm of the hand is facing you in the magnetic field, and the back of the hand is facing you in the magnetic field.

The four fingers represent the direction of the current.

The thumb represents the direction of the ampere.

Supplement: The relationship between the ampere force direction and the direction of the magnetic field and the direction of the current.

f b, f i, i.e., the plane determined by f perpendicular to b and i. The ampere force must be perpendicular to the magnetic field, but the direction of the current is not necessarily perpendicular to the direction of the magnetic field.

1. Judgment of ampere force direction.

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.

Use the left-hand rule to judge the direction of ampere force: stretch out the left hand, the thumb is perpendicular to the other four fingers, so that the direction of the four fingers is the same as the direction of the current, and the direction of the magnetic field line is perpendicular to the palm of the hand and penetrate the back of the hand, and the direction of the thumb is the direction of ampere force.

When the current direction of the wire is perpendicular to the direction of the magnetic inductance line, the ampere force is the largest; When the direction of the current is parallel to the direction of the magnetic inductance line, the minimum ampere force is zero.

2. Ampere rule and determination of ampere force.

Ampere's rule (right-hand spiral rule).

For straight wires, the thumb points in the direction of the current, and the direction of the four fingers is the direction of the magnetic inductance line; For annular current, the direction of the four fingers bending is the direction of the annular current, and the thumb points to the direction of the magnetic inductance line on the central axis; For long spirals, the direction in which the four fingers are bent is the direction in which the current in the solenoid is wrapped, and the thumb is pointed in the direction of the magnetic inductance line inside the solenoid.

The direction of the ampere.

The direction of the ampere force is perpendicular to the plane determined by b and i, that is, it must be perpendicular to b and i, but b and i are not necessarily perpendicular. Therefore, the left-handed rule is generally used to determine the direction of ampere force.

Determination of the direction of the Lorentz force.

The direction of the Lorentz force on the moving charged particle in the magnetic field is perpendicular to the direction of motion and the direction of the magnetic induction, and his pointing can be determined by the left-handed rule: extend the left hand, so that the thumb is perpendicular to the other four fingers, and all are in the same plane as the palm, let the magnetic inductance line enter from the palm, and the four fingers point to the direction of the positive charge movement, at this time, the direction pointed by the thumb is the direction of the Lorentz force of the moving positive charge in the magnetic field. The direction of the force on the negative charge is opposite to that of the positive charge.

The right-hand rule. Stretch out your right hand, so that your thumb is perpendicular to the other four fingers, and all of them are in the same plane as your palm, so that the magnetic lines enter perpendicular to the palm of your hand, your thumb points to the direction of the conductor's movement, and the other four fingers point to the direction of the induced current.

N pole out, S progression, so the current is from right to left.

In electromagnetism, the amount of electricity passing through any cross-section of a conductor per unit time is called current intensity, referred to as current, the current symbol is i, the unit is ampere (a), abbreviated as "ampere" (André Marie Ampère, 1775 1836, French physicist and chemist, outstanding achievements in the study of electromagnetic interaction, and also contributed to mathematics and physics). The SI unit of electric current is named after its surname).

The free charge in the conductor moves regularly and directionally under the action of the electric field force to form an electric current.

The direction of the positive charge-directed flow is the direction of the current. In addition, in the project, the directional flow direction of the positive charge is also the current direction, and the magnitude of the current is expressed by the charge Q flowing through the conductor section per unit time, which is called the current intensity.

1. Stretch out your right hand so that your thumb is perpendicular to the other four fingers and are all in the same plane as your palm; Let the magnetic wire enter from the palm of the hand and point the thumb in the direction of the wire movement, then the direction of the four fingers is the direction of the induced current.

2. This is the right-hand rule for determining the direction of the induced current when the wire cuts the magnetic inductance line. The right-hand rule judges the relationship between the direction of the current of the conductor cutting magnetic inductance line and the direction of the conductor movement. The right-hand spiral rule (Ampere's rule) determines the relationship between the direction of the current of an energized wire or coil and the direction of the magnetic inductance line.

The left-handed rule is used to determine the direction of the ampere force.

1.Extend the left hand, the thumb is perpendicular to the other four fingers, so that the direction of the four fingers is the same as the direction of the current, and the direction of the magnetic field line is perpendicular to the palm of the hand and the back of the hand, at this time the direction of the thumb is the direction of ampere. Principles of the left-handed rule:

The ampere force direction and the current direction are perpendicular to the direction of the magnetic field, that is, perpendicular to the direction of the plane composed of the current and the magnetic field.

2.The most important thing to judge is that the ampere force direction and the current direction are perpendicular to the magnetic field, and the specific positive and negative left-handed rule can be judged. The left-handed rule is John the British electrical engineer.

Ambrose. Fleming (Johnambrosefleming, 1849-1945).

Fleming was a professor of electrical engineering at the University of London, England, where students often misdirected magnetic fields, currents, and forces. So, he wanted to use a simple method to help students memorize. The "Left Hand Rule" was born.

Direction of ampere force: The direction of ampere force is perpendicular to the plane determined by the energized wire and the direction of the magnetic field, and the direction of i, b and f is determined by the left-hand rule.

If there is an electric current in the conductor, the electrons are moving, and the moving charge will be subjected to the Lorentz force in the magnetic field, and the macroscopic manifestation of the Lorentz force of a large number of electrons is the ampere force.

Ampere force is the force of the magnetic field that the current receives in the magnetic field, if the conductor length l, the passing current i, perpendicular to the magnetic field, the magnetic induction guess strength is b, and the magnitude of the ampere force is f=bil.

The direction of the ampere force is judged by the left-hand rule: stretch out the left hand, the four fingers are quietly in the direction of the current, let the magnetic field lines pass through the palm, and the direction of the thumb is the direction of the ampere force.

Overview: 1) Ampere's rule in energized straight wire, also known as Ampere's rule 1: Hold the energized straight wire with your right hand, so that your thumb points in the direction of the current, then the pointing of the four fingers is the direction around the magnetic inductance line.

2) Ampere's rule in energized solenoids, also known as Ampere's rule 2: Hold the energized solenoid with your right hand, so that the four-finger bend bridge is consistent with the direction of the current, then the end of the thumb is the n pole of the energized solenoid.

Judge ampere force with the left hand. Judge the ampere force to extend the left hand, so that the thumb is perpendicular to the other four fingers, and all are in the same plane as the palm, let the magnetic inductance line enter from the palm, and make the four fingers point in the direction of the current, then the direction of the thumb is the direction of the ampere force of the energized wire in the magnetic field. This is the left-handed rule that determines the direction in which an energized conductor is subjected to force in a magnetic field.

Ampere direction with the left hand. For straight wires, the thumb points in the direction of the current, the direction of the four fingers bent is the direction of the magnetic inductance line, and for the annular current, the direction of the four fingers bent is the direction of the annular current, and the thumb points to the direction of the magnetic inductance line on the central axis. So judge the ampere force with the left hand.

Judge the main application of ampere force

The ampere force is the resultant force of the Lorentz force on the charge that moves directionally in the body of Yu Shan. When the direction of the current is parallel to the magnetic field, the directional direction of the charge is also parallel to the direction of the magnetic field, and the Lorentz force is zero, and the resultant ampere force is also zero. Lorentz force does not do work because the direction of the force is perpendicular to the direction of motion of the particle.

The ampere force is perpendicular to the direction of the current in the wire, and the direction of movement of the wire is not necessarily perpendicular, and it is generally on the same vertical and vertical line, so the ampere force is not 0. The motion charge is positive, and the pointing of the thumb is the direction of the Lorentz force. Conversely, if the moving charge is negative and the direction of the charge motion is still indicated by four fingers, then the opposite direction of the thumb is the direction of the Lorentz force.