Which principle determines the direction of the magnetic field of the straight wire current

Left Hand Rule:

Left-handed rule (Ampere's rule): Knowing the direction of the current and the direction of the magnetic inductance line, the direction of the force on the energized conductor in the magnetic field, such as an electric motor.

Stretch out your left hand, let the magnetic line pass through the palm of your hand (palm aligned with the n pole, the back of the hand with the S pole), and the four fingers point to the direction of the current, then the direction of the thumb is the direction of the conductor force.

The principle is: when you draw the magnetic inductance lines of the magnet and the magnetic inductance lines of the current, the two magnetic inductance lines are intertwined, and according to the vector addition, where the magnetic inductance lines of the magnet and the current are in the same direction, the magnetic inductance lines become dense; In the opposite direction, the magnetic lines become sparse. One of the characteristics of magnetic inductance lines is that each magnetic inductance line repels each other! The pressure is high in places where magnetic inductance lines are dense, and the pressure is low in places where magnetic inductance lines are sparse.

So the pressure on both sides of the current is different, and the current is pressed to one side. The direction of the thumb is the direction of this pressure.

Right-Hand Rule: A rule that determines the direction of the induced current generated in the conductor when the conductor cuts the magnetic inductance line motion. (Generators).

The content of the right hand rule is: stretch out the right hand, so that the thumb is perpendicular to the other four fingers and are in the same plane as the palm, put the right hand into the magnetic field, let the magnetic inductance line perpendicular to the palm of the hand, the thumb points to the direction of the conductor movement, and the other four fingers point to the direction of the induced current.

How should I use the Left-Handed, Right-Handed, and Right-Hand Spiral Rule?

It's not a matter of memory. The content of the left-hand rule and the right-hand rule must be very clear to the students. The problem I encountered with a classmate was mainly that he didn't know whether to use the left-handed rule or the right-hand rule after getting a specific problem.

This is a key. The key to the problem is to ask students to figure out what the physical phenomenon is when the left-hand rule is applied and what kind of physical phenomenon the right-hand rule applies. The left-handed rule says that the magnetic field exerts force on an electric current, or the force exerted by a magnetic field on a moving charge.

In this case, you should use the left-handed rule, which is the key. After the judgment is made, it is time to use the left-handed rule, and the judgment is made according to the relationship between the three directions mentioned by the left-handed rule, and the problem will not be too big. The right-hand rule is the direction of movement of the induced current generated by the wire when the wire is cut in the magnetic field and the magnetic inductance line moves.

The direction of the magnetic field, the movement of the cutting magnetic inductance line, and the direction of the electromotive force are the way in which the current is induced. This kind of question is right-handed rule.

If you are an electronics student, you must master both hands. Be sure to keep it in mind.

The right-hand rule. Hold the wire with your right hand and your thumb pointing in the direction of the current, and the four-finger direction in the direction of the magnetic field lines.

If you are talking about a straight wire that is energized, then put it in a uniform magnetic field and the conductor will be moved by the action of the electromagnetic force f. The direction of the current does not change. What needs to be judged is the direction of movement of the conductor by electromagnetic force, and the relationship between the direction of current, magnetic field, and electromagnetic force can be judged by the left-handed rule

Stretch out the left hand, the thumb is perpendicular to the other four fingers, the magnetic field lines pass through the palm of the hand (that is, the palm of the hand faces the n pole), the direction of the four fingers is the direction of the current, and the direction of the thumb is the direction of the force of the energized conductor (that is, the direction of the electromagnetic force f).

If you're talking about straight wires, it's not energized. Then put it in a uniform magnetic field and do the cutting magnetic field line motion. Then an induced electromotive force will be generated in the conductor (according to the law of electromagnetic induction), where the relationship between the direction of the current, the direction of the conductor motion, and the direction of the magnetic field can be used by the right-hand rule:

Stretch out the right hand, the thumb is perpendicular to the other four fingers, the magnetic field lines pass through the palm of the hand (that is, the palm of the hand faces the n pole), the direction of the thumb is the direction of movement of the conductor, then the direction of the four fingers is the direction of inducing electromotive force (that is, the direction of inducing current).

The left-hand rule applies to electric motors, while the right-hand rule applies to generators.

The direction of the magnetic field and the direction of the current.

When there is a change in the direction of current and magnetic field, the direction of force of the energized wire will change, but when the direction of current and the direction of the magnetic field change at the same time, the direction of force of the energized wire will not change.

In the process of electrons jumping from one atom to another, there must be the disappearance and re-establishment of the electric field, in this process the electric field is changed, the magnetic field is excited, for no electron, the strength of the magnetic field is different, but the whole wire is macroscopically stable.

Energized wires are contraindicated by magnetic fields.

The understanding of the uniform radial distribution of the magnetic field means that the extension line of all magnetic inductance lines passes through the center of the iron core, no matter what position the coil is in, the angle between the coil plane and the magnetic inductance line is zero degrees, the magnetic field is not a uniform magnetic field, but on the circle centered on the iron core, the magnitude of the magnetic induction intensity b at each point is equal, and such a magnetic field can make the magnetic field strength of the position where the two sides pass through the same when the coil rotates, so that the scale of the dial is uniform.

The advantage of magnetoelectric instruments is that they are highly sensitive and can measure very weak currents, while the disadvantage is that the wires that wind the coil are very thin, and the current allowed to pass through them is very weak (tens of microamperes to a few milliamps). If the current passing through exceeds the allowable value, it can easily burn out.

The above content refers to Encyclopedia - Magnetic Field of Energized Straight Wire.

The direction of the magnetic field generated by the energized wire, which is related to the direction of the current in the wire.

It is related to the direction of the current, which is different in the direction of the current and the direction of the surrounding of the resulting magnetic field. The relationship between a linear current and the magnetic field generated by that current can be determined by Ampere's rule:

Ampere's rule: Ampere's rule in energized straight wires: Hold the energized straight wire with your right hand and let your thumb point in the direction of the current, then the pointing of the four fingers is the direction around the magnetic inductance line;

So the magnetic field generated by the linear current is a circle. The specific clockwise or counterclockwise can be judged by the ampere's rule.

This is the problem of ampere, which involves three physical quantities: the direction of the magnetic field, the direction of the current, and the direction of the ampere, if you know two of the directions, you can use the left-handed rule to find the other direction. Specifically, stretch out the left palm and put the thumb in the direction perpendicular to the other four fingers into the magnetic field, the direction of the back of the palm corresponds to the direction of the magnetic inductance line (that is, the magnetic inductance line exceeds the palm), the direction of the four fingers corresponds to the direction of the conductor current, and the direction of the thumb corresponds to the direction of the ampere force.

According to the left-handed rule.

Stretch out the left hand, the thumb and palm are perpendicular and coplanar, the magnetic calendar line passes inward through the palm, and the four fingers point in the direction of the current, then the thumb points to the ampere force.

direction, so it can be obtained that the ampere force level in figure a is to the right, so a is wrong;

In Figure B, the vertical middle is searched straight up, so B is wrong; In the C diagram, the direction of perpendicular and current is upward, so C is wrong; In the D diagram, the vertical current direction is upward, so D is correct

Therefore, choose D

A brief explanation is below to see if it helps.

The electro-generated magnetic Oersted experiment shows that there is a magnetic field around the energized wire, and the direction of the magnetic field is related to the direction of the current, which is called the magnetic effect of the current.

The magnetic field on the outside of an energized solenoid is very similar to that of a bar magnet. The two ends of the energized solenoid are equivalent to the two poles of a bar magnet, and their magnetic properties can be determined experimentally by pointing the small magnetic needle, the external magnetic field of the energized solenoid starts from the n pole and returns to the S pole, and the inside points from the S pole to the n pole. With amperdine, the n-pole of the solenoid can be determined by the direction of the current.

The phenomenon of magnetic generation of electricity due to the movement of conductors in a magnetic field is a phenomenon of electromagnetic induction, and the current generated is called induced current.

Conditions for induced current: When a part of the conductor of a closed circuit moves to cut magnetic inductance lines in a magnetic field, an induced current is generated in the conductor. The phenomenon of electromagnetic induction is the principle of generators.

The right-hand rule: one is Ampere's rule, hold the solenoid with your right hand, let the four fingers point to the direction of the current in the solenoid, then the end of the thumb is the n pole of the solenoid. Second, it is suitable for the generator palm is the direction of the magnetic field, the thumb is the direction of the object movement, and the finger is the direction of the current, and the direction of the dynamic electromotive force generated in the conductor when the conductor cuts the magnetic inductance line.

Note: The object is a straight wire, and the velocity v and magnetic field b must be perpendicular to the wire, and v and b must be perpendicular to each other, and the right-hand rule cannot be used to determine the direction of the induced electromotive force.

Left-handed rule: The relationship between the direction of the magnetic field, the direction of the current, and the direction of the force exerted by the magnetic field on the current can be expressed by the "left-handed rule". Extend your left palm so that your thumb and four fingers are vertical.

Put the left palm into the magnetic field, so that the magnetic inductance line passes from the palm of the hand to the back of the hand (that is, the palm of the hand is opposed to the n poles), and make the four fingers point in the direction of the current, and the thumb refers to the direction of the current by the magnetic field.

Ampere's rule: A rule that expresses the relationship between the direction of the magnetic inductance line of the current and the magnetic field excited by the current.

Answer A test question analysis: The force of the magnetic field on the energized straight wire is called ampere force, and the relationship between the direction of the magnetic field, the direction of the current and the direction of the ampere force is: the direction of the ampere force must be perpendicular to the direction of the magnetic field, the direction of the ampere force must be perpendicular to the current side of the rock, and the direction of the magnetic field and the direction of the current are not necessarily perpendicular.

Therefore, choose the A test center: the direction of ampere.

Comments: Easy question. The direction of the ampere force is always perpendicular to both the direction of the magnetic field and the direction of the current, that is to say, the direction of the ampere force is always perpendicular to the plane determined by the magnetic field and the current.

Therefore, when judging, first determine the plane of the magnetic field and the current lead, so as to determine which straight line the direction of the ampere force is, and then judge the specific direction of the ampere force according to the left-hand rule.

According to the rule of the left hand, the palm of the left hand is the direction in which the magnetic field enters the field, the four fingers are the direction of the current, and the thumb is the direction of the force.

So choose c, perpendicular to the direction of the magnetic field and perpendicular to the direction of the current.

The slope of the straight line y=kx+b is the ruler brother k, and the oblique collision rate of the primary function of the line is also kIn this problem, the primary function parallel to y=2x+1 must be y=2x+b, substituting the point (2,-1) to get b=-5, and the answer is y=2x-5