How to determine the direction of the current generated when a conductor moves in a magnetic field

First, use the right-hand rule to determine the direction of induced electromotive force: stretch out the right hand, let the magnetic field lines pass perpendicularly through the palm, that is, the palm is facing the n pole, so that the thumb perpendicular to the four fingers points to the direction of the movement of the conductor cutting the magnetic field lines, then the direction pointed by the straight four fingers is the direction of the induced electromotive force, as shown in Figure +, No.

Direction of induced current: The current is generated when the conductor and the external circuit (as shown in the red line in the figure) form a loop, and the conductor plays the role of power supply in the loop. Thus, the induced current flows from the negative electrode of the electromotive force to the positive electrode within the conductor and from the positive electron electron force to the negative electrode outside the conductor.

If you are a student, you can really only use the right-hand rule for the exam, you can look at the direction of the current on the conduit, if the flow direction is to the lower right or the upper left is the right direction, if the flow direction is the lower left or the upper right is the left direction, do not turn your hand over and over when judging the direction of the current, it is easy to mess up.

First of all. To clarify such a definition:

i.e. the right-hand rule (generator rule):

The left-handed rule (the law of electric motors).

The conductor cuts the magnetic inductance lines as it moves in a magnetic field.

The generation of induced electromotive force exists as a power source.

as a generator.

That is, the right-hand rule, that is, the direction of the palm corresponding to the magnetic field.

Thumb table direction of movement.

The remaining four fingers indicate the direction of the current.

When the conductor moves in a magnetic field, it induces an electric current and the direction of the conductor's movement, that is, cutting the magnetic inductance line.

The direction is related to the direction of the magnetic field, so changing the direction of the conductor movement and the direction of the magnetic field can be achieved to change the ammeter.

The direction in which the pointer is deflection.

The induced current always hinders the change of the magnetic field: if the magnetic field increases, the force will hinder him from increasing....In the same way, the magnetic field reduces the ampere force and does not let him decrease....By knowing the direction of the magnetic field, and knowing the ampere force, the left-hand rule can judge the current....

If only the children's shoes on the energized straight wire said very clearly...

Answer: Application"Right Hand Spiral Rule".The four fingers are curved; application".The right-hand rule"Spread out your fingers and be on the same plane as your palm.

Detailed analysis: 1. First of all, we must figure out what the two rules are to determine respectively.

The right-hand spiral determination determines the relationship between the direction of the magnetic field generated by the energized straight wire and the direction of the current.

The right-hand rule determines the relationship between the direction of the induced current and the direction of the magnetic field and the direction of movement of the conductor to cut the magnetic inductance line.

2. Specific judgment method:

Right-handed spiral rule: Hold the wire with your right hand (Four fingers are bent), the thumb points in the direction of the current, and the four fingers are bent to point in the direction of the magnetic inductance line.

The rule of the right hand: Stretch out the right hand, the five fingers and the palm are in the same plane, the palm of the hand passes through the magnetic inductance line, the thumb points to the direction of the conductor movement, and the four fingers point to the direction of the induced current.

To use your right palm well, remember that the four fingers represent the direction of the magnetic field, pay attention to the direction of the hand grip, and the thumb is the direction of the current.

1. If the wire cuts the magnetic field and generates an electric current, use the right hand rule: the right hand is flattened, 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, 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).

2. If the energized wire is subjected to force in the magnetic field, use the left-hand rule: the left hand is flat, and the palm is facing the direction of the magnetic inductance line, so that the thumb is perpendicular to the other four fingers, and all of them are in a plane with the palm. Put your left hand into the magnetic field, let the magnetic inductance line penetrate vertically into your palm, and point your four fingers in the direction of the current, then the direction of your thumb is the direction of the force on the conductor.

Use (d) to determine the direction of the magnetic field generated by the electric current.

a.The left-handed rule.

b.The right-hand rule

c.Electric motor rule.

d.Ampere's rule

Ampere's rule, also known as the right-hand spiral rule, is a rule that expresses the relationship between the direction of the magnetic inductance line of the electric current and the magnetic field excited by the current. Ampere's rule in energized straight wire (Ampere's rule 1): Hold the energized straight wire with your right hand and point your thumb in the direction of the current in the straight wire, then the four fingers pointing is the direction of the magnetic field around the energized wire.

Ampere's rule in energized solenoids (Ampere's rule 2): Hold the energized solenoid with your right hand so that the four fingers point in the direction of the current, then the end of the thumb is the n pole of the energized solenoid.

The basic definition is as follows:

The amperometric rule for straight-line currents also applies to a small section of straight-line currents. The annular current can be regarded as composed of multiple small linear currents, and the direction of the magnetic inductance intensity on the central axis of the annular current is determined by the ampere rule of the linear current for each small linear current.

The direction of the magnetic inductance line on the mandrel of the rolling beam in the annular current is obtained. The ampere rule of linear current is basic, and the ampere rule of annular current can be derived from the ampere's statute of linear current.

The Ampere's rule of linear currents also applies to the magnetic field generated by the linear motion of the charge, where the direction of the current is the same as that of the positive charge and opposite to that of the negative charge.

Right-handed spiral rule: Assuming that you hold an energized wire with your right hand and your thumb pointing in the direction of the current, then the bent four fingers indicate 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.

It is used to determine the direction of the magnetic field generated by an electric current (Ampere's rule).

There is a magnetic field around the current, and the direction of the magnetic field is related to the direction of the current, and the direction of the magnetic field outside the energized solenoid is also related to the direction of the current, and its relationship can be judged by the right-hand spiral rule. The rule that shows the relationship between the direction of the magnetic inductance line of the current and the magnetic inductance of the current excitation magnetic field is called the right-hand spiral rule, and this rule is also often called the Ampere rule.

Overview of the right-hand rule

1. In electromagnetism, the right-hand rule mainly judges the direction independent of force. If it's about force, it's all about the left-handed rule. That is, the left-handed rule is used for forces, and the right-handed rule is used for others (generally used to determine the direction of the induced current).

This point is often confused, and it can be found that the word "force" is left-handed, so use the left hand; And the word "electricity" is withdrawn to the right, just use the right hand) to memorize the formula: left and right to generate electricity. It can also be remembered as:

Use your left hand for electricity and your right hand for electricity.

2. You can use the direction of the palm and fingers of the right hand to remember the direction of the current generated when the wire cuts the magnetic inductance line, that is: stretch out the right 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 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. This is the right-hand rule that determines the direction of the current induced when the wire cuts the magnetic inductance line.

There are two ways to determine the direction of the magnetic field generated by an electric current, which are the Ampere's right-handed method and Faraday's left-handed rule.

Ampere's right-handed method:

The ampere-right-handed method uses the thumb, index finger, and middle finger to represent the direction of the three vectors to determine the direction of the magnetic field generated by the electric current. Here's how:

1) Straighten your right hand so that your palm is facing up;

2) Point the index finger of your right hand in the direction of the square potato pants of the current (the current starts from the positive pole and points to the negative pole);

3) Bend the middle finger of your right hand perpendicular to your index finger and point at the point you are ready to judge;

4) Finally, the direction of the right thumb is the direction of the magnetic field generated by the electric current.

Faraday's left-handed rule:

Faraday's left hand used his left hand to determine the direction of the magnetic field generated by the electric current. Here's how:

1) Hold your left hand in a half-grip position so that your thumb, index finger, and middle finger are perpendicular to each other and extend them in different directions at the same time.

2) Make a fist with your index finger, which represents the direction of the magnetic field forward, i.e., the line that extends from the emitting source and perpendicular to the direction of the needle.

3) Bend the middle finger to represent the direction of the current, i.e. the line that follows the direction of the current from the source of emission.

4) The direction represented by the last thumb is the direction of the magnetic field.

It is important to note that when using both methods, it is important to determine the direction of the current, the direction of the magnetic field, and the direction of the fingers or palms. At the same time, it is necessary to understand a basic principle: when an electric current passes through a conductor, it generates a magnetic field, so when we know the direction of the current, we can determine the direction of the resulting magnetic field by the Ampere's right-handed method or Faraday's left-handed rule.

The condition is that a part of the closed circuit is the movement of the conductor in the magnetic field to cut the magnetic inductance lines.

The conditions for the generation of induced current: first, the circuit is closed and closed; The second is the change in the magnetic flux of the dispersion and closure of the closed circuit. (If a condition is missing, no induced current will be generated).

When a conductor cuts magnetic field lines to the left or right, the area enclosed by the closed circuit changes, and so does the magnetic flux passing through that area. The cause of the induced current in a conductor can be attributed to a change in the magnetic flux passing through the closed circuit.

It can be seen that whenever the magnetic flux passing through the closed circuit changes, an induced current is generated in the closed circuit. This is the condition under which the induced current is generated.

The two ends of the conductor are connected to the two binding posts of the ammeter to form a closed circuit, when the conductor moves left or right in the magnetic field and cuts the magnetic field lines, the pointer of the ammeter is deflected, indicating that the current generated in the circuit is called induced current.

When the conductor moves to the left or right, the deflection direction of the ammeter pointer is different, indicating that the direction of the induced current is related to the direction of the conductor's movement.

If the direction of the conductor's motion is kept unchanged, and the two magnetic poles are reversed, i.e., the direction of the magnetic field lines is changed, and the direction of the induced current is also changed. It can be seen that the direction of the induced current is related to the direction of the conductor's motion and the direction of the magnetic field lines.

The conductor does not necessarily produce an electric current in the magnetic field, but it is possible to generate an induced current when the two ends of the conductor form a loop with the outside world or the conductor itself forms a loop, otherwise only the induced electromotive force can be generated.

Regarding the induced electromotive force generated, it is divided into kinetic electromotive force and induced electromotive force.

For circuits, the dynamic electromotive force is generally the electromotive force generated by the movement of the circuit that is not parallel to the magnetic inductance line while the magnetic field is stable and does not change (taking a uniform magnetic field as an example). There is also a situation that the trace combustion circuit moves perpendicular to the magnetic inductance line in a uniform magnetic field without inducing current: for example, a rectangular coil is perpendicular to the direction of the magnetic field, and the direction of motion is perpendicular to the direction of the magnetic field, but at the same time, the direction of motion is perpendicular to the two opposite sides of the coil.

For heterogeneous magnetic fields, the movement of the loop changes the magnetic flux in the loop to generate induced electromotive force and induced current.

Induced electromotive force (EMF) is an electromotive force generated by a change in the magnetic flux in the loop due to a change in the magnetic flux of the circuit instead of a relative motion occurring in the circuit. The value is the rate of change of the magnetic flux relative to time, multiplied by the number of turns of the coil.