Rules of right and left hand physics explanation. Left hand rule. The left hand rule can be used to determine the direction of the force with which a magnetic field acts on individual moving charges.
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 direction
To figure it out, you still have to remember school lessons. At them, physics teachers told us that electric current is the movement of elementary particles, which at the same time carry their charge along a 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 of the magnetic field, a couple of conductors begin to act according to completely different scenarios: either repel each other, or, on the contrary, rush towards.
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 - the path of movement 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.
DETERMINATION OF THE DIRECTION OF THE MAGNETIC FIELD LINES
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 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.
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 a 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 with current interact with each other? 
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.
I look forward to making decisions in the next lesson on "5"!
It is known that superconductors (substances that have almost zero electrical resistance at certain temperatures) 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.
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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.
. 
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 smaller 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 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:
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 enclosed in it, and when moving in a magnetic field of electric charges, a force will act on them according to the left hand rule.
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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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 a modern person, it would be more common to use 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 a 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. The main feature is that the lines of the magnetic field pass 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 is 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:
Rules of the left and right hand
The right hand rule is the rule used to determine the magnetic induction vector of the field.
This rule also has the names "rule of gimlet" and "rule of the screw", due to the similarity of the principle of operation. It is widely used in physics, as it allows, without the use of special instruments or calculations, to determine the most important parameters - angular velocity, moment of force, moment of impulse. In electrodynamics, this method allows you to determine the vector of magnetic induction. 
gimlet rule
The rule of a gimlet or screw: if the palms of the right hand are placed so that it coincides with the direction of the current in the conductor under study, then the translational rotation of the gimlet handle (thumb of the palm) will indicate directly the vector of magnetic induction.
In other words, it is necessary to screw in a drill or a corkscrew with your right hand to determine the vector. There are no particular difficulties in mastering this rule.
There is another version of this rule. Most often, this method is simply called the “right hand rule”.
It sounds like this: in order to determine the direction of the lines of induction of the generated magnetic field, you need to take the conductor with your hand so that the thumb left at 90 ° shows the direction of the current flowing through it. 
There is a similar option for the solenoid.
In this case, you should grab the device so that the fingers of the palm coincide with the direction of the current in the turns. The protruding thumb in this case will show where the magnetic field lines come from.
Right hand rule for a moving conductor
This rule will also help in the case of conductors moving in a magnetic field. Only here it is necessary to act somewhat differently.
The open palm of the right hand should be positioned so that the field lines of force enter it perpendicularly. The outstretched thumb should indicate the direction of movement of the conductor. With this arrangement, the outstretched fingers will coincide with the direction of the induction current.
As we can see, the number of situations where this rule really helps is quite large.
The first rule of the left hand
It is necessary to place the left palm in such a way that the field induction lines enter it at a right angle (perpendicular). The four outstretched fingers of the palm should coincide with the direction of the electric current in the conductor. In this case, the extended thumb of the left palm will show the direction of the force acting on the conductor. 
In practice, this method allows you to determine the direction in which a conductor with an electric current passing through it, placed between two magnets, will begin to deviate.
The second rule of the left hand
There are other situations where you can use the left hand rule. In particular, to determine the forces with a moving charge and a stationary magnet.
Another rule of the left hand says: The palm of the left hand should be positioned in such a way that the lines of induction of the created magnetic field enter into it perpendicularly. The position of the four outstretched fingers depends on the direction of the electric current (along the movement of positively charged particles, or against negative ones). The protruding thumb of the left hand in this case will indicate the direction of the Ampere force or the Lorentz force.
The advantage of the rules of the right and left hand lies precisely in the fact that they are simple and allow you to accurately determine important parameters without the use of additional instruments. They are used in various experiments and tests, and in practice when it comes to conductors and electromagnetic fields.
soloproject.com
- 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 smaller 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:
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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 electric current flows. 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 maximum 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 current-carrying conductor 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 use of this action is based on the device of electric motors that convert electrical energy into mechanical energy, 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. By the action of a magnetic field 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 enclosed in it, and when moving in a magnetic field of electric charges, a force will act on them according to the left hand rule.
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 Aleksandrovna
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 one
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 and the field created by the current interact, 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.
Force 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!")
Anyone who has chosen electrical engineering as his main profession is very well aware of some of the basic properties of electric current and its accompanying magnetic fields. One of the most important of them is the gimlet rule. On the one hand, it is rather difficult to call this rule a law. It is more correct to say that we are talking about one of the fundamental properties of electromagnetism.
What is the gimlet rule? Although the definition exists, for a more complete understanding it is worth remembering the basics of electricity. As is known from the school physics course, electric current is the movement of elementary particles that carry an electric charge along any conductive material. Usually it is compared with interatomic movement, which, due to external influences (for example, a magnetic impulse), receive a portion of energy sufficient to leave their established orbit in the atom. Let's do a thought experiment. To do this, we need a load, an EMF source and a conductor (wire) connecting all the elements into a single closed circuit.
The source creates a directed movement of elementary particles in the conductor. At the same time, back in the 19th century, it was noticed that around such a conductor arises which rotates in one direction or another. The gimlet rule just allows you to determine the direction of rotation. The spatial configuration of the field is a kind of tube, in the center of which there is a conductor. It would seem: what difference does it make how this generated magnetic field behaves! However, Ampere noticed that two current-carrying conductors act on each other with their magnetic fields, repelling or attracting each other, depending on the direction of rotation of their fields. Later, on the basis of a number of experiments, Ampère formulated and substantiated his law of interaction (by the way, it underlies the operation of electric motors). Obviously, without knowing the gimlet rule, it is very difficult to understand the ongoing processes.
In our example, it is known - from "+" to "-". Knowing the direction makes it easy to use the gimlet rule. Mentally, we begin to screw a gimlet with a standard right-hand thread into the conductor (along it) so that the result is coaxial with the direction of current flow. In this case, the rotation of the handle will coincide with the rotation of the magnetic field. You can use another example: we screw in an ordinary screw (bolt, screw).
This rule can be used a little differently (although the basic meaning is the same): if you mentally wrap your right hand around a current-carrying conductor so that four bent fingers point in the direction in which the field rotates, then the bent thumb will indicate the direction of the current flowing through the conductor . Accordingly, the opposite is also true: knowing the direction of the current, "grasping" the wire, you can find out the direction of the rotation vector of the generated magnetic field. This rule is actively used in the calculation of inductors, in which, depending on the direction of the turns, it is possible to influence the flowing current (creating, if necessary, a countercurrent).
The gimlet's law allows us to formulate a consequence: if the right palm is placed in such a way that the lines of intensity of the generated magnetic field enter it, and four straightened fingers point to the known direction of movement of charged particles in the conductor, then the thumb bent at an angle of 90 degrees will indicate the direction of the vector force that exerts a displacing effect on the conductor. By the way, it is this force that creates a torque on the shaft of any electric motor.
As you can see, there are quite a few ways to use the above rule, so the main “difficulty” lies in the selection by each person that is clear to him.