Test verification 1. A magnetic field is generated electric shock. 2. A magnetic field is created by moving charged particles. 3. The direction of the magnetic line at any point is conventionally taken to be the direction indicated by the north pole of the magnetic needle placed at this point. 4. Magnetic lines leave the north pole of the magnet and enter the south pole.

LEFT HAND RULE for a charged particle If the LEFT HAND is positioned so that the magnetic field lines enter the palm perpendicular to it, and four fingers are directed along the movement of a positively charged particle (or against the movement of a negatively charged particle), then the thumb placed at 90 degrees will show the direction of the force acting on the particle.

Is it possible to protect yourself from the effects of magnetic forces? Oddly enough, the substance impermeable to magnetic forces is the same iron that is so easily magnetized! Inside the iron ring, the compass needle is not deflected by a magnet placed outside the ring. It is magnetized

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Electromagnetic field

Let's repeat How can we experimentally show the connection between the direction of the current in a conductor and the direction of its magnetic field lines? Formulate the gimlet rule. What can you determine using the gimlet rule? State the right hand rule for the solenoid. What can be determined using the right hand rule?

Independent work The figure shows the position of the conductor section connected to the current source and the position of the magnetic line. Determine its direction. + A. Clockwise B. Counterclockwise C. From us D. To us -

Independent work 2. Which figure correctly shows the picture of the magnetic field lines of a long conductor with a direct current directed perpendicular to the plane of the drawing away from us? 1 2 3 4 A. 1 B. 2 C. 3 D. 4

Independent work 3. Current flows through the conductor from us. Determine the direction of the magnetic line of this current. A. Clockwise B. Counterclockwise C. To us D. From us

Independent work 4 . Current flows through the conductor towards us. Determine the direction of the magnetic line of this current. A. Clockwise B. Counterclockwise C. To us D. From us

Independent work 5. The figure shows a picture of the magnetic lines of a straight conductor carrying current. The magnetic field is weakest A. At point A B. At point B C. At point C D. At point D G B C A

Detection of a magnetic field by its effect on electric current. Left hand rule.

A current-carrying conductor placed in a magnetic field is acted upon by a force from the magnetic field.

A magnetic field is created by an electric current and is detected by its effect on the electric current.

Left hand rule N N S S

Rule of the left hand If you position your left hand so that: 4 fingers are directed along the current; Magnetic lines entered the palm perpendicularly; then the thumb placed at 90° will show the direction of the force acting on the conductor.

Left hand rule for particles

Left hand rule for a positively charged particle 4 fingers are directed along the movement of the + charged particle; Magnetic lines enter the palm perpendicularly; = the thumb positioned at 90° will indicate the direction of the force acting on the conductor.

We consolidate Exercise No. 36 p. 155

presentation on the topic: "Rule of the left hand. Power of Ampere"

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Lesson in 9th grade on the topic:“Detection of a magnetic field by its effect on an electric current. Left hand rule.Ampere power».

Lesson objectives:

Educational:

study how a magnetic field is detected by its effect on an electric current, study the left-hand rule, repeat the previously covered definitions of the electric field, magnetic field, the conditions for their occurrence, properties; consolidate the rules of the right and left hands with the help of exercises;

consolidate knowledge on previous topics;

teach to apply the knowledge acquired in the lesson;

show connection with life;

expand interdisciplinary connections.

Educational:

to form an interest in the subject, in learning, to cultivate initiative, a creative attitude, to cultivate a conscientious attitude towards learning, to instill skills like independent work, and work in a team, to cultivate a cognitive need and interest in the subject.

Developmental:

develop students’ physical thinking, their creative abilities, the ability to independently formulate conclusions, expand cognitive interest by attracting additional material, as well as the need to deepen and expand knowledge;

develop speech skills;

develop the ability to highlight the main thing, draw conclusions, develop the ability to quickly perceive information and perform the necessary tasks; develop logical thinking and attention, the ability to analyze, compare the results obtained, and draw appropriate conclusions.

Lesson steps:

1. Organizational moment – ​​2 min.
2. Check homework, knowledge and skills – 6 min.
3. Explanation of new material – 18 min.
4. Consolidation. Problem solving – 15 min.
5. Results. Conclusions. Homework – 4 min.

DURING THE CLASSES

I . Checking homework, knowledge and skills – 6 min

Slide 2.

1. The magnetic field is generated by______________ (electric current).

2. The magnetic field is created by ______________charged particles (moving).

3. The direction of the magnetic line at any point is conventionally taken to be the direction indicated by the _________ pole of the magnetic needle placed at this point (north).
4. Magnetic lines leave the _________ pole of the magnet and enter the ________. (Northern, southern).

We exchanged papers and checked each other. The correct answers are displayed on the screen.

Slide 3.

Correct answers: 4 answers – 5 points, 3 answers – 4 points, 2 answers – 3 points, 0-1 answers – 2 points.

II . Explanation of new material – 15 min

Slide 4.

Teacher: How can a magnetic field be detected? It does not affect our senses - it has no smell, color, or taste. We cannot, however, say with certainty that in the animal world there are no creatures that sense a magnetic field. In the United States and Canada, electromagnetic barriers have been installed to drive octopuses away from their fry aggregation sites on rivers flowing into the Great Lakes. Scientists explain the ability of fish to navigate the ocean by their reaction to magnetic fields...

Today in class we will learn how to detect a magnetic field by its effect on an electric current and learn the left hand rule.

For any current-carrying conductor placed in a magnetic field and not coinciding with its magnetic lines, this field acts with some force; the presence of such a force can be seen using the following experiment: the conductor is suspended on flexible wires, which are connected to the batteries through a key. The conductor is placed between the poles of a horseshoe magnet, i.e. it is in a magnetic field. When the key is closed, an electric current appears in the circuit, and the conductor begins to move. If you remove the magnet, then when the circuit is closed, the current-carrying conductor will not move. (Demonstration of experience)

Slide 5.

If students can answer for themselves: This means that from the side of the magnetic field, a certain force acts on the current-carrying conductor, deflecting it from its original position. This force is called the Ampere force.

Let's find out what determines the direction of the Ampere force acting on a conductor with current in a magnetic field. Experience shows that when the direction of the current changes, the direction of movement of the conductor also changes, and therefore the direction of the force acting on it.

The direction of the force will also change if, without changing the direction of the current, the poles of the magnet are swapped (that is, the direction of the magnetic field lines is changed).
Consequently, the direction of the current in the conductor, the direction of the magnetic field lines and the direction of the force acting on the conductor are interconnected.

Slide 6.

The direction of the force acting on a current-carrying conductor in a magnetic field can be determined using the left-hand rule. In the simplest case, when the conductor is located in a plane perpendicular to the magnetic field lines, this rule is as follows: if the left hand is positioned so that the magnetic field lines enter the palm perpendicular to it, and four fingers are directed along the current, then the left hand 90 ° the thumb will indicate the direction of the force acting on the conductor.

Students: The direction of current in the external part of the electrical circuit (i.e. outside the current source) is taken to be the direction from the positive pole of the current source to the negative.

Using the left-hand rule, you can determine not only the direction of the force acting in a magnetic field on a current-carrying conductor. Using this rule, we can determine the direction of the current (if we know the directions of the magnetic field lines and the force acting on the conductor), the direction of the magnetic lines (if the directions of the current and force are known), and the sign.
The force of a magnetic field on a current-carrying conductor is zero if the direction of the current in the conductor coincides with the magnetic field lines or is parallel to them.

Slide 7.

Use of Ampere force in technology:

Electric motors;

Electrical measuring instruments;

Loudspeakers, speakers.

IV . Fixing the material. Problem solving – 15 min.

Slide 8.

Slide 9.

Slide 10.

Teacher: Ex. 36(1). In which direction will the light aluminum tube roll when the circuit is closed?

Students give the answers: according to the left-hand rule, the magnetic field lines enter the palm, the electric current flows through the tube, which means the tube will roll towards the current source.

Results

Today in class we learned how to detect a magnetic field by its effect on an electric current. We studied the Ampere force and its application in technology. We considered the left-hand rule for determining the direction of the Ampere force.

Slide 11.

V . § 46, ex. 36 (2, 3, 4, 5).

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“9th grade _Left hand rule_”

Detection of a magnetic field by its effect on electric current. Left hand rule. Force Ampere.

Fill in the missing words.

• 1. The magnetic field is generated by ___________.
• 2 . A magnetic field is created by ______________ charged particles.
• 3. The direction of the magnetic line at any point is conventionally taken to be the direction that indicates the _________ pole of the magnetic needle placed at this point.
• 4. Magnetic lines leave the _________ pole of the magnet and enter the ________.

• 1. The magnetic field is generated electric shock .
• 2 . Magnetic field is created moving charged particles.
• 3. The direction of the magnetic line at any point is conventionally taken to be the direction that indicates northern the pole of a magnetic needle placed at this point.
• 4. Magnetic lines come out northern poles of the magnet and enter into southern .

• From the side of the magnetic field, a certain force acts on the current-carrying conductor, deflecting it from its original position.
• The direction of the current in the conductor, the direction of the magnetic field lines and the direction of the force acting on the conductor are interconnected.
• This force is called Ampere forces(F A).

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

• How the conductor shown in the figure will move. The direction of the current is shown by arrows.

• Between the poles of the magnets there are current-carrying conductors. How does each one move?

• Exercise 36. Task No. 1.

• Exercise 36 (2,3,4,5) written in a notebook

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Now let's move on to determining the poles of the coil with current. We must again determine the direction of the current in a similar way. After that, we do almost the same thing, only we leave the fingers straighter, but bent. We approach our coil and direct our fingers (all except the protruding thumb) in the direction of the current in it, i.e. our fingers have become, as it were, not whole turns of the coil). In this case, the thumb points in the direction of the north pole of the coil. Now let's move on to determining the poles of the coil with current. We must again determine the direction of the current in a similar way. After that, we do almost the same thing, only we leave the fingers straighter, but bent. We approach our coil and direct our fingers (all except the protruding thumb) in the direction of the current in it, i.e. our fingers have become, as it were, not whole turns of the coil). In this case, the thumb points in the direction of the north pole of the coil. P.S. A slight digression) the finger also shows the direction of the magnetic lines PASSING THROUGH the coil, and vice versa - shows the direction OPPOSITE to the lines passing outside the coil and “entering its south pole.

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