For those who were not good at physics at school, the gimlet rule is still a real “terra incognita” today. Especially if you try to find the definition of a well-known law on the Web: search engines will immediately give you a lot of intricate scientific explanations with complex schemes. However, it is quite possible to briefly and clearly explain what it consists of.

What is the gimlet rule

Gimlet - a tool for drilling holes

It sounds like this: in cases where the direction of the gimlet coincides with the direction of the current in the conductor during translational movements, then the direction of rotation of the gimlet handle will also be identical to it.

Looking for directions

To figure it out, you still have to remember school lessons. On them, physics teachers told us that electric current is movement elementary particles, which carry their charge along the conductive material. Due to the source, the movement of particles in the conductor is directed. Movement, as you know, is life, and therefore around the conductor there is nothing but a magnetic field, and it also rotates. But how?

It is this rule that gives the answer (without using any special tools), and the result turns out to be very valuable, because depending on the direction magnetic field a couple of conductors begin to act according to completely different scenarios: either repel each other, or, on the contrary, rush towards each other.

Usage

The easiest way to determine the path of movement of magnetic field lines is to apply the gimlet rule

You can imagine it this way - using the example of your own right hand and the most ordinary wire. We put the wire in our hand. Clench four fingers tightly into a fist. The thumb points up, like a gesture that we use to show that we like something. In this “layout”, the thumb will clearly indicate the direction of the current, while the other four will indicate the path of the magnetic field lines.

The rule is quite applicable in life. Physicists need it in order to determine the direction of the magnetic field of the current, calculate the mechanical rotation of the speed, the vector of magnetic induction and the moment of forces.

By the way, the fact that the rule is applicable to a variety of situations is also evidenced by the fact that there are several interpretations of it at once - depending on each specific case under consideration.

With the help of left and right hand rules, you can easily find and determine the directions of the current, magnetic lines, as well as other physical quantities.

Gimlet and right hand rule

The gimlet rule was first formulated famous physicist Peter Buravchik. It is convenient to use it to determine the direction of tension. So, the wording of the rule is as follows: in the case when the gimlet, moving forward, is screwed in the direction of the electric current, the direction of the handle of the gimlet itself must coincide with the direction of the magnetic field. This rule can be applied with a solenoid: we grab the solenoid, the fingers should point in the same direction as the current, that is, show the path of the current in the turns, then stick out the thumb of the right hand, it points to the desired path of the magnetic induction lines.

According to statistics, the rule of the right hand is used much more often than the rule of the gimlet, partly due to a more understandable wording, it says: we grab the object with the right hand, while the clenched fingers of the fist should show the direction of the magnetic lines, and the thumb protruding approximately 90 degrees should show the direction electric current. If a moving conductor is present: the arm should be turned so that lines of force of this field were perpendicular to the palms (90 degrees), the protruding thumb should point to the path of the conductor, then 4 bent fingers will point to the path induction current.

left hand rule

The left hand rule has two formulations. The first formulation says: the hand should be placed so that the remaining bent fingers of the hand indicate the path of the electric current in this conductor, the lines of induction should be perpendicular to the palm, and the left thumb extended indicates the force acting on this conductor. The following wording says: four bent fingers, except for the thumb, are located exactly along the movement of negatively charged or positively charged electric current, and the induction lines should be directed perpendicularly (90 degrees) to the palm, in this case, the large one in this case should show the flow Ampere force or Lorentz force.

The gimlet rule or the right hand rule was first formulated by Peter Gimlet. It determines the direction of the magnetic field strength, which

is in a straight line to a current-carrying conductor.

The main rule that is used in variants of the screw or gimlet rule and in the formulation of the right hand rule is the direction selection rule. vector product and bases. It is quite simple to remember: if a gimlet with a right-hand thread is screwed in the direction of the current, then the direction of rotation of the handle of the gimlet itself coincides with the direction of the magnetic field, which is excited by the current (Fig. 1).

It is necessary to grab the conductor with the right hand so that the thumb shows the direction of the current, then the remaining fingers will show the lines of magnetic induction that go around this conductor and the fields that are created by the current, as well as the direction of the magnetic induction vector, which is directed everywhere tangentially to the lines. If a current is passed through the wire, then a magnetic field will also arise around the wire.

If the wire consists of several turns and the axes of these turns coincide, then it is called a solenoid (Fig. 2).

rice. 2

The magnetic field is excited when current passes through one turn (winding) of the solenoid. Its direction depends on the direction of the current.

The presented field of the solenoid rings is very similar to the field permanent magnet. The direction of the solenoid field lines can be determined using the gimlet rule, as well as the right hand rule. A freely rotating magnetic needle, placed near a conductor with current, which forms a magnetic field, tends to take a perpendicular position of the plane that runs along it.

The right hand rule for a solenoid is that if the solenoid is clasped with the right hand so that four fingers point in the direction of the current in the coils, then the thumb will point in the direction of the magnetic field lines in the solenoid itself.

With the translational movement of the gimlet coinciding with the direction of the current in the conductor, then rotational movements the handle of the gimlet will indicate the direction of the magnetic field lines that arise around the conductor. If the right hand is placed so that it includes all the lines of force of the magnetic field, and the big one is placed in the direction of the conductor, then four fingers will indicate the direction of the induction current.

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A simple explanation of the gimlet rule

Name Explanation

Most people remember the mention of this from the course of physics, namely the section of electrodynamics. It happened for a reason, because this mnemonic is often given to students to simplify the understanding of the material. In fact, the gimlet rule is used both in electricity, to determine the direction of a magnetic field, and in other sections, for example, to determine the angular velocity.

A gimlet is a tool for drilling small diameter holes in soft materials, for modern man it would be more customary to cite a corkscrew as an example.

Important! It is assumed that the gimlet, screw or corkscrew has a right-hand thread, that is, the direction of its rotation, when twisting, is clockwise, i.e. to the right.

The video below provides the full wording of the gimlet rule, be sure to watch it to understand the whole point:

How is the magnetic field related to the gimlet and hands

In problems in physics, when studying electrical quantities, one often encounters the need to find the direction of the current, along the vector of magnetic induction, and vice versa. Also, these skills will be required when solving complex problems and calculations related to the magnetic field of systems.

Before proceeding to the consideration of the rules, I want to recall that the current flows from a point with a large potential to a point with a lower one. It can be put simply - the current flows from plus to minus.

The gimlet rule has the following meaning: when screwing the tip of the gimlet along the direction of the current, the handle will rotate in the direction of the vector B (the vector of magnetic induction lines).

The right hand rule works like this:

Place your thumb as if you are showing "class!", Then turn your hand so that the direction of the current and the finger match. Then the remaining four fingers will coincide with the magnetic field vector.

Visual analysis of the right hand rule:

To see this more clearly, conduct an experiment - scatter metal shavings on paper, make a hole in the sheet and thread the wire, after applying current to it, you will see that the shavings are grouped into concentric circles.

Magnetic field in the solenoid

All of the above is true for a straight conductor, but what if the conductor is wound into a coil?

We already know that when current flows around a conductor, a magnetic field is created, a coil is a wire coiled around a core or mandrel many times. The magnetic field in this case is amplified. A solenoid and a coil are basically the same thing. main feature in that the lines of the magnetic field run in the same way as in the situation with a permanent magnet. The solenoid is a controlled analogue of the latter.

The right hand rule for a solenoid (coil) will help us determine the direction of the magnetic field. If you take the coil in your hand so that four fingers look in the direction of current flow, then the thumb will point to vector B in the middle of the coil.

If you twist the gimlet along the turns, again in the direction of the current, i.e. from the "+" terminal to the "-" terminal of the solenoid, then the sharp end and the direction of movement as lies the magnetic induction vector.

In simple words, where you twist the gimlet, the lines of the magnetic field go there. The same is true for one turn (circular conductor)

Determining the direction of the current with a gimlet

If you know the direction of the vector B - magnetic induction, you can easily apply this rule. Mentally move the gimlet along the direction of the field in the coil with the sharp part forward, respectively, clockwise rotation along the axis of movement and show where the current flows.

If the conductor is straight, rotate the corkscrew handle along the specified vector so that this movement is clockwise. Knowing that it has a right-hand thread, the direction in which it is screwed in coincides with the current.

What is connected with the left hand

Do not confuse the gimlet and the left hand rule, it is necessary to determine the force acting on the conductor. The straightened palm of the left hand is located along the conductor. The fingers point in the direction of current flow I. Field lines pass through the open palm. The thumb coincides with the vector of force - this is the meaning of the rule of the left hand. This force is called the Ampere force.

You can apply this rule to a single charged particle and determine the direction of 2 forces:

Imagine that a positively charged particle is moving in a magnetic field. The lines of the magnetic induction vector are perpendicular to the direction of its movement. You need to put the open left palm with your fingers in the direction of the charge movement, the vector B should penetrate the palm, then the thumb will indicate the direction of the vector Fa. If the particle is negative, the fingers look against the direction of the charge.

If at some point you were not clear, the video clearly shows how to use the left hand rule:

It's important to know! If you have a body and a force is acting on it that tends to turn it, turn the screw in this direction, and you will determine where the moment of force is directed. If we talk about the angular velocity, then the situation is as follows: when the corkscrew rotates in the same direction as the rotation of the body, it will screw in the direction of the angular velocity.

It is very easy to master these methods of determining the direction of forces and fields. Such mnemonic rules in electricity greatly facilitate the tasks of schoolchildren and students. Even a full kettle will deal with a gimlet if it has opened wine with a corkscrew at least once. The main thing is not to forget where the current flows. I repeat that the use of a gimlet and the right hand is most often successfully used in electrical engineering.

You probably don't know:

A MAGNETIC FIELD

- this is a special kind of matter, through which the interaction between moving electrically charged particles is carried out.

PROPERTIES OF A (STATIONARY) MAGNETIC FIELD

Permanent (or stationary) A magnetic field is a magnetic field that does not change with time.

1. Magnetic field created moving charged particles and bodies, conductors with current, permanent magnets.

2. Magnetic field valid on moving charged particles and bodies, on conductors with current, on permanent magnets, on a frame with current.

3. Magnetic field vortex, i.e. has no source.

are the forces with which current-carrying conductors act on each other.

.

- this is power characteristic magnetic field.

The magnetic induction vector is always directed in the same way as a freely rotating magnetic needle is oriented in a magnetic field.

The unit of measurement of magnetic induction in the SI system:

LINES OF MAGNETIC INDUCTION

- these are lines, tangent to which at any point is the vector of magnetic induction.

Uniform magnetic field- this is a magnetic field, in which at any of its points the magnetic induction vector is unchanged in magnitude and direction; observed between the plates of a flat capacitor, inside a solenoid (if its diameter is much less than its length), or inside a bar magnet.

Magnetic field of a straight conductor with current:

where is the direction of the current in the conductor on us perpendicular to the plane of the sheet,
- the direction of the current in the conductor from us is perpendicular to the plane of the sheet.

Solenoid magnetic field:

Magnetic field of bar magnet:

- similar to the magnetic field of the solenoid.

PROPERTIES OF MAGNETIC INDUCTION LINES

- have direction
- continuous;
-closed (i.e. the magnetic field is vortex);
- do not intersect;
- according to their density, the magnitude of the magnetic induction is judged.

DIRECTION OF MAGNETIC INDUCTION LINES

- is determined by the gimlet rule or by the right hand rule.

Gimlet rule (mainly for a straight conductor with current):

Right hand rule (mainly for determining the direction of magnetic lines
inside the solenoid):

There are other possible options applying the rules of the gimlet and the right hand.

is the force with which a magnetic field acts on a current-carrying conductor.

The Ampere force module is equal to the product of the current strength in the conductor and the module of the magnetic induction vector, the length of the conductor and the sine of the angle between the magnetic induction vector and the direction of the current in the conductor.

The Ampere force is maximum if the magnetic induction vector is perpendicular to the conductor.

If the magnetic induction vector is parallel to the conductor, then the magnetic field has no effect on the conductor with current, i.e. Ampere's force is zero.

The direction of the Ampere force is determined by left hand rule:

If the left hand is positioned so that the component of the magnetic induction vector perpendicular to the conductor enters the palm, and 4 outstretched fingers are directed in the direction of the current, then the thumb bent 90 degrees will show the direction of the force acting on the conductor with current.

or

ACTION OF A MAGNETIC FIELD ON A LOOP WITH A CURRENT

A uniform magnetic field orients the frame (i.e., a torque is created and the frame rotates to a position where the magnetic induction vector is perpendicular to the plane of the frame).

An inhomogeneous magnetic field orients + attracts or repels the frame with current.

So, in the magnetic field of a direct current-carrying conductor (it is non-uniform), the current-carrying frame is oriented along the radius of the magnetic line and is attracted or repelled from the direct current-carrying conductor, depending on the direction of the currents.

Remember the topic "Electromagnetic phenomena" for grade 8:

class-fizika.narod.ru

Determining the direction of magnetic field lines. The gimlet rule. Right hand rule

GIM RULE for a straight conductor with current

- serves to determine the direction of magnetic lines (lines of magnetic induction)
around a straight current-carrying conductor.

If direction forward movement gimlet coincides with the direction of the current in the conductor, then the direction of rotation of the gimlet handle coincides with the direction of the lines of the magnetic field of the current.

Suppose a conductor with current is located perpendicular to the plane of the sheet:
1. email direction current from us (to the sheet plane)

According to the gimlet rule, magnetic field lines will be directed clockwise.

Then, according to the gimlet rule, the magnetic field lines will be directed counterclockwise.

RIGHT HAND RULE for solenoid, i.e. coils with current

- serves to determine the direction of magnetic lines (lines of magnetic induction) inside the solenoid.

If you grasp the solenoid with the palm of your right hand so that four fingers are directed along the current in the turns, then the thumb set aside will show the direction of the magnetic field lines inside the solenoid.

1. How do 2 coils interact with each other with current?

2. How are the currents in the wires directed if the interaction forces are directed as in the figure?

3. Two conductors are parallel to each other. Indicate the direction of current in the LED conductor.

Looking forward to the next lesson on "5"!

It is known that superconductors (substances that at certain temperatures have almost zero electrical resistance) can create very strong magnetic fields. Experiments have been made to demonstrate such magnetic fields. After cooling the ceramic superconductor with liquid nitrogen, a small magnet was placed on its surface. The repulsive force of the magnetic field of the superconductor was so high that the magnet rose, hovered in the air and hovered over the superconductor until the superconductor, when heated, lost its extraordinary properties.

Right and left hand rule in physics: application in everyday life

Entering adulthood, few people remember the school physics course. However, sometimes it is necessary to delve into the memory, because some knowledge gained in youth can greatly facilitate the memorization of complex laws. One of these is the right and left hand rule in physics. Its application in life allows you to understand complex concepts (for example, to determine the direction of the axial vector with a known basis). Today we will try to explain these concepts and how they work in a language accessible to a simple layman who graduated a long time ago and forgot unnecessary (as it seemed to him) information.

Read in the article:

The wording of the gimlet rule

Piotr Buravchik is the first physicist to formulate the left hand rule for various particles and fields. It is applicable both in electrical engineering (it helps to determine the direction of magnetic fields), and in other areas. It will help, for example, to determine the angular velocity.

Gimlet rule (right hand rule) - this name is not associated with the name of the physicist who formulated it. More the name relies on a tool that has a certain direction of the auger. Usually, a gimlet (screw, corkscrew) has a so-called. the thread is right-handed, the drill enters the ground clockwise. Consider the application of this statement to determine the magnetic field.

You need to clench your right hand into a fist, raising your thumb up. Now we slightly unclench the other four. They show us the direction of the magnetic field. In short, the gimlet rule has the following meaning - by screwing the gimlet along the direction of the current, we will see that the handle rotates in the direction of the line of the magnetic induction vector.

The right and left hand rule: application in practice

In considering the application of this law, let's start with the right hand rule. If the direction of the magnetic field vector is known, with the help of a gimlet one can do without knowledge of the law electromagnetic induction. Imagine that the screw moves along the magnetic field. Then the direction of current flow will be "along the thread", that is, to the right.

Let's pay attention to the permanent controlled magnet, the analog of which is the solenoid. At its core, it is a coil with two contacts. It is known that the current moves from "+" to "-". Based on this information, we take the solenoid in the right hand in such a position that 4 fingers indicate the direction of the current flow. Then the outstretched thumb will indicate the vector of the magnetic field.

Application of the right hand rule for a solenoid

The left hand rule: what can be determined using it

Do not confuse the rules of the left hand and gimlet - they are designed for completely different purposes. With the help of the left hand, two forces can be determined, or rather, their direction. It:

Let's try to figure out how it works.

Application for ampere force

The left hand rule for Ampère's power: what it is

Place the left hand along the conductor so that the fingers point in the direction of current flow. The thumb will point in the direction of the Ampère force vector, and in the direction of the hand, between the thumb and forefinger, the magnetic field vector will be directed. This will be the left hand rule for the ampere force, the formula of which looks like this:

Left hand rule for the Lorentz force: differences from the previous one

We arrange the three fingers of the left hand (thumb, index and middle) so that they are at right angles to each other. The thumb, directed in this case to the side, will indicate the direction of the Lorentz force, the index finger (pointed down) - the direction of the magnetic field (from the north pole to the south), and the middle one, located perpendicular to the side of the big one - the direction of the current in the conductor.

The formula for calculating the Lorentz force can be seen in the figure below.

Conclusion

Having dealt once with the rules of the right and left hand, the dear reader will understand how easy it is to use them. After all, they replace the knowledge of many laws of physics, in particular, electrical engineering. The main thing here is not to forget the direction of current flow.

With the help of hands, you can determine many different parameters

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Experiment

A current-carrying conductor is a source of a magnetic field.

If a current-carrying conductor is placed in an external magnetic field,

then it will act on the conductor with the force of Ampere.

Amp power is the force with which a magnetic field acts on a current-carrying conductor placed in it.

André Marie Ampère

The effect of a magnetic field on a conductor with current was investigated experimentally

André Marie Ampère (1820).

By changing the shape of the conductors and their location in a magnetic field, Ampère was able to determine the force acting on a separate section of the current-carrying conductor (current element). In his honor

this force was called the Ampère force.

– ampere power

According to experimental data, the modulus of force F :

proportional to the length of the conductor l located in a magnetic field;

proportional to the magnetic field induction modulus B ;

proportional to the current in the conductor I ;

depends on the orientation of the conductor in the magnetic field, i.e. from the angle α between the direction of the current and the magnetic field induction vector B ⃗ .

Ampere force module

Ampere's force modulus is equal to the product of the magnetic field induction modulus B ,

in which there is a conductor with current,

the length of this conductor l , current I in it and the sine of the angle between the directions of the current and the magnetic field induction vector

Direction

Ampere forces

The direction of the Ampère force is determined

according to the rule left arms:

if the left hand is placed

so that the magnetic field induction vector (B⃗) enters

in the palm, four outstretched

fingers pointing in the direction

current (I), then the thumb bent 90 ° will indicate the direction of the Ampère force (F⃗ A).

Interaction of two

conductors with current

A current-carrying conductor creates a magnetic field around itself

the second conductor with current is placed in this field,

which means that Ampere's force will act on it

Action

magnetic field

on the frame with current

A couple of forces act on the frame, as a result of which it rotates.

• The direction of the force vector is determined by the rule of the left hand.
• F=B I l sinα=ma
• M=F d=B I S sinα- in torque

Electrical measuring

appliances

Magnetoelectric system

Electromagnetic system

Interaction

coil magnetic field

with steel core

Interaction

loops with current and magnet fields

Application

Ampere forces

The forces acting on a current-carrying conductor in a magnetic field are widely used in engineering. Electric motors and generators, devices for recording sound in tape recorders, telephones and microphones - in all these and in many other devices and devices, the interaction of currents, currents and magnets is used.

A task

A straight conductor with a length of 0.5 m, through which a current of 6 A flows, is in a uniform magnetic field. Module of the magnetic induction vector 0.2 T, the conductor is located at an angle

to the vector AT .

Force acting on the conductor from the side

magnetic field is equal to

Answer: 0.3 N

Answer

Solution.

The Ampere force acting from the side of the magnetic field on a current-carrying conductor is determined by the expression

Correct answer: 0.3 N

Solution

Examples:

- to us

Without a clue

- from U.S

Apply the left hand rule to fig. Nos. 1,2,3,4.

Rice#3

Rice#2

Rice#4

Rice#1

Where is located N pole in fig. 5,6,7?

Rice#7

Rice#5

Rice#6

Internet resources

http://fizmat.by/kursy/magnetizm/sila_Ampera

http://www.physbook.ru/index.php/SA._%D0%A1%D0%B8%D0%BB%D0%B0_%D0%90%D0%BC%D0%BF%D0%B5% D1%80%D0%B0

http://class-fizika.narod.ru/10_15.htm

http://www.physics.ru/courses/op25part2/content/chapter1/section/paragraph16/theory.html#.VNoh5iz4uFg

http://www.eduspb.com/node/1775

http://www.ispring.ru

- this is a special kind of matter, through which the interaction between moving electrically charged particles is carried out.

PROPERTIES OF A (STATIONARY) MAGNETIC FIELD

Permanent (or stationary) A magnetic field is a magnetic field that does not change with time.

1. Magnetic field created moving charged particles and bodies, conductors with current, permanent magnets.

2. Magnetic field valid on moving charged particles and bodies, on conductors with current, on permanent magnets, on a frame with current.

3. Magnetic field vortex, i.e. has no source.

are the forces with which current-carrying conductors act on each other.

.

is the force characteristic of the magnetic field.

The magnetic induction vector is always directed in the same way as a freely rotating magnetic needle is oriented in a magnetic field.

The unit of measurement of magnetic induction in the SI system:

LINES OF MAGNETIC INDUCTION

- these are lines, tangent to which at any point is the vector of magnetic induction.

Uniform magnetic field- this is a magnetic field, in which at any of its points the magnetic induction vector is unchanged in magnitude and direction; observed between the plates of a flat capacitor, inside a solenoid (if its diameter is much less than its length), or inside a bar magnet.

Magnetic field of a straight conductor with current:

where is the direction of the current in the conductor on us perpendicular to the plane of the sheet,
- the direction of the current in the conductor from us is perpendicular to the plane of the sheet.

Solenoid magnetic field:

Magnetic field of bar magnet:

- similar to the magnetic field of the solenoid.

PROPERTIES OF MAGNETIC INDUCTION LINES

- have direction
- continuous;
-closed (i.e. the magnetic field is vortex);
- do not intersect;
- according to their density, the magnitude of the magnetic induction is judged.

DIRECTION OF MAGNETIC INDUCTION LINES

- is determined by the gimlet rule or by the right hand rule.

Gimlet rule (mainly for a straight conductor with current):

If the direction of the translational movement of the gimlet coincides with the direction of the current in the conductor, then the direction of rotation of the gimlet handle coincides with the direction of the lines of the magnetic field of the current.

Right hand rule (mainly for determining the direction of magnetic lines
inside the solenoid):

If you grasp the solenoid with the palm of your right hand so that four fingers are directed along the current in the turns, then the thumb set aside will show the direction of the magnetic field lines inside the solenoid.

There are other possible applications of the gimlet and right hand rules.

is the force with which a magnetic field acts on a current-carrying conductor.

The Ampere force module is equal to the product of the current strength in the conductor and the module of the magnetic induction vector, the length of the conductor and the sine of the angle between the magnetic induction vector and the direction of the current in the conductor.

The Ampere force is maximum if the magnetic induction vector is perpendicular to the conductor.

If the magnetic induction vector is parallel to the conductor, then the magnetic field has no effect on the conductor with current, i.e. Ampere's force is zero.

The direction of the Ampere force is determined by left hand rule:

If the left hand is positioned so that the component of the magnetic induction vector perpendicular to the conductor enters the palm, and 4 outstretched fingers are directed in the direction of the current, then the thumb bent 90 degrees will show the direction of the force acting on the conductor with current.

or

ACTION OF A MAGNETIC FIELD ON A LOOP WITH A CURRENT

A uniform magnetic field orients the frame (i.e., a torque is created and the frame rotates to a position where the magnetic induction vector is perpendicular to the plane of the frame).

An inhomogeneous magnetic field orients + attracts or repels the frame with current.

So, in the magnetic field of a direct current-carrying conductor (it is non-uniform), the current-carrying frame is oriented along the radius of the magnetic line and is attracted or repelled from the direct current-carrying conductor, depending on the direction of the currents.

Remember the topic "Electromagnetic phenomena" for grade 8:

class-fizika.narod.ru

The effect of a magnetic field on a current. Left hand rule.

Let us place a conductor between the poles of a magnet, through which a constant current flows. electricity. We will immediately notice that the conductor will be pushed out of the interpolar space by the field of the magnet.

This can be explained as follows. Around the conductor with current (Figure 1.) Forms its own magnetic field, the lines of force of which on one side of the conductor are directed in the same way as the lines of force of the magnet, and on the other side of the conductor - in the opposite direction. As a result, on one side of the conductor (on the top in Figure 1) the magnetic field turns out to be concentrated, and on its other side (on the bottom in Figure 1) it is rarefied. Therefore, the conductor experiences a force pressing down on it. And if the conductor is not fixed, then it will move.

Figure 1. Effect of a magnetic field on current.

left hand rule

To quickly determine the direction of movement of a conductor with current in a magnetic field, there is a so-called left hand rule(picture 2.).

Figure 2. Left hand rule.

The rule of the left hand is as follows: if you place the left hand between the poles of the magnet so that the magnetic lines of force enter the palm, and the four fingers of the hand coincide with the direction of the current in the conductor, then the thumb will show the direction of movement of the conductor.

So, on a conductor through which an electric current flows, a force acts, tending to move it perpendicular to the magnetic lines of force. Empirically, you can determine the magnitude of this force. It turns out that the force with which the magnetic field acts on a current-carrying conductor is directly proportional to the current strength in the conductor and the length of that part of the conductor that is in the magnetic field (Figure 3 on the left).

This rule is true if the conductor is located at right angles to the magnetic lines of force.

Figure 3. The strength of the interaction of the magnetic field and current.

If the conductor is not located at right angles to the magnetic field lines, but, for example, as shown in Figure 3 on the right, then the force acting on the conductor will be proportional to the current strength in the conductor and the length of the projection of the part of the conductor located in the magnetic field, on a plane perpendicular to the magnetic lines of force. It follows that if the conductor is parallel to the magnetic lines of force, then the force acting on it is zero. If the conductor is perpendicular to the direction of the magnetic field lines, then the force acting on it reaches its greatest value.

The force acting on a conductor with current also depends on the magnetic induction. The denser the magnetic field lines are, the greater the force acting on the current-carrying conductor.

Summing up all of the above, we can express the action of a magnetic field on a conductor with current by the following rule:

The force acting on a conductor with current is directly proportional to the magnetic induction, the current strength in the conductor and the length of the projection of the part of the conductor located in the magnetic field onto a plane perpendicular to the magnetic flux.

It should be noted that the effect of the magnetic field on the current does not depend on the substance of the conductor, nor on its cross section. The effect of a magnetic field on a current can be observed even in the absence of a conductor, by passing, for example, a stream of rapidly moving electrons between the poles of a magnet.

The action of a magnetic field on a current is widely used in science and technology. The device of electric motors is based on the use of this action, converting electrical energy into mechanical, the device of magnetoelectric devices for measuring voltage and current strength, electrodynamic loudspeakers that turn electrical vibrations into sound, special radio tubes - magnetrons, cathode ray tubes, etc. The effect of a magnetic field on current is used to measure the mass and charge of an electron, and even to study the structure of matter.

Right hand rule

When a conductor moves in a magnetic field, a directed movement of electrons is created in it, that is, an electric current, which is due to the phenomenon of electromagnetic induction.

For determining directions of electron movement Let's use the well-known rule of the left hand.

If, for example, a conductor located perpendicular to the drawing (Figure 1) moves along with the electrons contained in it from top to bottom, then this movement of electrons will be equivalent to an electric current directed from bottom to top. If at the same time the magnetic field in which the conductor moves is directed from left to right, then to determine the direction of the force acting on the electrons, we will have to put the left hand with the palm to the left so that the magnetic lines of force enter the palm, and with four fingers up (against the direction of movement conductor, i.e. in the direction of the "current"); then the direction of the thumb will show us that the electrons in the conductor will be affected by a force directed from us to the drawing. Consequently, the movement of electrons will occur along the conductor, i.e., from us to the drawing, and the induction current in the conductor will be directed from the drawing to us.

Picture 1. The mechanism of electromagnetic induction. By moving the conductor, we move together with the conductor all the electrons contained in it, and when moving in a magnetic field electric charges force will act on them according to the rule of the left hand.

However, the rule of the left hand, applied by us only to explain the phenomenon of electromagnetic induction, turns out to be inconvenient in practice. In practice, the direction of the induction current is determined right hand rule(Figure 2).

Figure 2. Right hand rule. The right hand is turned with the palm towards the magnetic lines of force, the thumb is directed in the direction of the movement of the conductor, and four fingers show in which direction the induction current will flow.

Right hand rule is that, if you place your right hand in a magnetic field so that the magnetic lines of force enter the palm, and the thumb indicates the direction of movement of the conductor, then the remaining four fingers will show the direction of the induction current that occurs in the conductor.

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The direction of the current and the direction of the lines of its magnetic field. Left hand rule. Physics teacher: Murnaeva Ekaterina Alexandrovna. - presentation

Presentation on the topic: » The direction of the current and the direction of the lines of its magnetic field. Left hand rule. Physics teacher: Murnaeva Ekaterina Alexandrovna. - Transcript:

1 The direction of the current and the direction of the lines of its magnetic field. Left hand rule. Physics teacher: Murnaeva Ekaterina Alexandrovna

2 Methods for determining the direction of a magnetic line Determining the direction of a magnetic line Using a magnetic needle According to the Gimlet rule or according to the right hand rule According to the left hand rule

3 Direction of magnetic lines

4 Right hand rule Grasp the solenoid with the palm of your right hand, pointing four fingers in the direction of the current in the coils, then the left thumb will show the direction of the magnetic field lines inside the solenoid

5 Rule of the gimlet

6 BB B In which direction does the current flow in the conductor? up wrong down right up right down wrong left wrong right right

7 How is the magnetic induction vector directed at the center of the circular current? + – up wrong down right + – up right down wrong + – right right left wrong _ + right wrong left right

8 Left hand rule If the left hand is positioned so that the lines of the magnetic field enter the palm perpendicular to it, and four fingers are directed along the current, then the thumb set aside by 90 ° will show the direction of the force acting on the conductor.

9 Application The orienting action of the MP on the circuit with current is used in electrical measuring instruments: 1) electric motors 2) electrodynamic loudspeaker (speaker) 3) magnetoelectric system - ammeters and voltmeters

10 Three installations of devices are assembled according to the schemes shown in the figure. In which of them: a, b or c - will the frame rotate around the axis if the circuit is closed?

11 11 Three installations of devices a, b, c are assembled. In which of them will the conductor AB move if the key K is closed?

12 In the situation shown in the figure, the action of the Ampère force is directed: A. Up B. Down C. Left D. Right

13 In the situation shown in the figure, the action of the Ampere force is directed: A. Up B. Down C. Left D. Right

14 In the situation shown in the figure, the action of the Ampère force is directed: A. Up B. Down C. Left D. Right

15 From the figure, determine how the magnetic lines of the direct current magnetic field are directed A. Clockwise B. Counterclockwise

16 What magnetic poles are shown in the figure? A. 1 north, 2 south B. 1 south, 2 south C. 1 south, 2 north D. 1 north, 2 north

17 The steel magnet was broken into three pieces. Will ends A and B be magnetic? A. They won’t B. End A has a north magnetic pole, C has a south one C. End C has a north magnetic pole, A has a south

18 From the figure, determine how the magnetic lines of the direct current MP are directed. A. Clockwise B. Counterclockwise

19 Which of the figures correctly shows the position of the magnetic needle in the magnetic field of a permanent magnet? A B C D

20 §§45,46. Exercise 35, 36. Homework:

Direction of current left hand rule

If the conductor through which the electric current passes is introduced into a magnetic field, then as a result of the interaction of the magnetic field and the conductor with current, the conductor will move in one direction or another.
The direction of movement of the conductor depends on the direction of the current in it and on the direction of the magnetic field lines.

Let us assume that in the magnetic field of a magnet N S there is a conductor located perpendicular to the plane of the figure; current flows through the conductor in the direction from us beyond the plane of the figure.

The current flowing from the plane of the figure to the observer is conventionally denoted by a dot, and the current flowing beyond the plane of the figure from the observer is denoted by a cross.

The movement of a conductor with current in a magnetic field
1 - magnetic field of the poles and conductor current,
2 is the resulting magnetic field.

Always everything leaving in the images is indicated by a cross,
and directed at the viewer - a point.

Under the action of a current around the conductor, its own magnetic field is formed (Fig. 1 .
Applying the gimlet rule, it is easy to verify that in the case we are considering, the direction of the magnetic lines of this field coincides with the direction of the clockwise movement.

When the magnetic field of the magnet interacts with the field created by the current, the resulting magnetic field is formed, shown in Fig. 2 .
The density of the magnetic lines of the resulting field on both sides of the conductor is different. To the right of the conductor, magnetic fields, having the same direction, add up, and to the left, being directed oppositely, they partially cancel each other out.

Therefore, a force will act on the conductor, which is greater on the right and less on the left. Under the action of a greater force, the conductor will move in the direction of the force F.

Changing the direction of the current in the conductor will change the direction of the magnetic lines around it, as a result of which the direction of movement of the conductor will also change.

To determine the direction of movement of a conductor in a magnetic field, you can use the left hand rule, which is formulated as follows:

If the left hand is positioned so that the magnetic lines pierce the palm, and the outstretched four fingers indicate the direction of the current in the conductor, then the bent thumb will indicate the direction of movement of the conductor.

The force acting on a current-carrying conductor in a magnetic field depends on both the current in the conductor and the intensity of the magnetic field.

The main quantity characterizing the intensity of the magnetic field is the magnetic induction AT . The unit of measurement for magnetic induction is tesla ( Tl=Vs/m2 ).

Magnetic induction can be judged by the strength of the magnetic field on a current-carrying conductor placed in this field. If the conductor is long 1m and with current 1 A , located perpendicular to the magnetic lines in a uniform magnetic field, a force acts in 1 N (Newton), then the magnetic induction of such a field is equal to 1 T (tesla).

Magnetic induction is a vector quantity, its direction coincides with the direction of the magnetic lines, and at each point of the field the magnetic induction vector is directed tangentially to the magnetic line.

Strength F , acting on a conductor with current in a magnetic field, is proportional to the magnetic induction AT , current in the conductor I and conductor length l , i.e.
F=BIl .

This formula is true only if the current-carrying conductor is located perpendicular to the magnetic lines of a uniform magnetic field.
If a conductor with current is in a magnetic field at any angle a with respect to magnetic lines, then the force is equal to:
F=BIl sin a .
If the conductor is placed along magnetic lines, then the force F becomes zero because a=0 .

(Detailed and intelligible in the video course "Into the world of electricity - like for the first time!")