Repeatedly generalizing lesson on the topic of electromagnetic induction. Electromagnetic induction (lesson development). Comments and suggestions for the future

Lesson objectives:

1. Testing and consolidating students' knowledge on this topic.
2. Development of knowledge systematization skills.
3. Fostering a sense of responsibility for your studies.

Equipment:

1. Ceramic magnets.
2. Lenz device.
3. Galvanometer, coil, arc-shaped magnet.
4. Alternator.
5. Constructor “Geomag”.
6. Didactic materials “A.E. Maron 11th grade.”
7. Disc “Lessons of Cyril and Methodius” 10th grade lessons No. 28-31.

Lesson progress

I. Greetings, introduction to the lesson plan.

1. Hello guys, today we will have a general lesson on the topic “Magnetic field. Electromagnetic induction.” Guests present at the lesson are physics teachers from our region. They also have wonderful students like you, they will worry and worry about you, so let's answer calmly and confidently.

2. Guys, at the end of today's lesson you will all receive grades. This grade will be derived from the arithmetic average of the three grades you must receive during the lesson. You will receive your first mark for telling a rule or explaining a formula. You will earn a second mark for solving a problem on the board or explaining experiments that I will demonstrate and which you will see on the screen. You will receive the third grade for tests that contain three tasks.

3. Guys, before we start work, let’s remember what we know today about the most ordinary magnets?

Answer: Magnet in translation means “loving stone”; people have long been treated with magnets, the soul was prescribed to magnets, a magnet has two poles.

II. Knowledge test.

1. Explaining the rules and explaining the formulas. (They are written on the board in advance)

Rules: gimlet, left hand, Lenz

Definition: phenomena of electromagnetic induction, self-induction

Fa=B|I| L sin a
Fл=|q|vB sin a
Ф=BS cos a
E=vBL sin a
Eis=-L I/t
Wm=LI * I/2

3. On the board there are drawings for the problems - students go out one by one and find the unknown quantity.

4. The teacher shows experiments, the children explain (they have already seen these experiments in previous lessons)

a) with ceramic magnets – interaction of magnets;
b) Lenz device - the phenomenon of electromagnetic induction;
c) galvanometer, coil, magnet - the appearance of alternating electric current;
d) generator - the light comes on.

5. Footage is shown on the screen, students explain what they are talking about

6. Question: what is common between self-induction and inertia?
7. What rule we learned does the following picture resemble? See Appendix 1
8. Working with tests from didactic material.

After 5 minutes I show the correct answers and the rating scale.

III. Summing up.

1. We give ourselves grades and take the arithmetic average.
2. We hand in sheets of marks.

IV. Summarizing the lesson, thanking the students for their good work.

VI. Homework:

Prepare a message about the use of all the forces and the phenomenon that we have repeated today in modern technology.

Details

By type, this is a lesson in studying and consolidating new material, which is conducted as a research lesson. The lesson uses a multimedia presentation. This lesson uses individual and collective forms of learning organization. During the lesson, the verbal method was used, the visual method was the illustration method (poster) and demonstration method (experience, presentation), as well as the problem presentation method. During the lesson, student-centered learning is used.

The lesson introduces the basic concepts of electrodynamics: electromagnetic induction, induced current, the relationship between magnetic and electric fields. The lesson uses activity-based learning technology, the main emphasis is on students’ independent work to acquire new knowledge. A problematic situation is created. Schoolchildren know that a magnetic field appears around a current-carrying conductor. Can a magnetic field produce an electric current?

During the lesson, a differentiated approach was used in the form of a multi-level test.

Lesson topic: “The phenomenon of electromagnetic induction”

Lesson type: lesson on comprehensive acquisition of knowledge, skills, abilities

Teaching methods: explanatory-illustrative, reproductive, partially search.

Forms of organization of cognitive activity:

· frontal (frontal conversation at all stages of the lesson);

· group

Lesson objectives:

· educational: to study the phenomenon of electromagnetic induction and the conditions for its occurrence, to show cause-and-effect relationships when observing the phenomenon of electromagnetic induction, to promote the actualization, consolidation and generalization of acquired knowledge, and the independent construction of new knowledge;

· developing: promote the development of the ability to work in a group, develop logical thinking and attention, the ability to analyze, compare the results obtained, and draw appropriate conclusions.

· educational: to cultivate cognitive need and interest in the subject;

Equipment: strip magnet, connecting wires, galvanometer, milliammeter, coils, current source, key, coil, arc-shaped magnet, rheostat, transformer, device for demonstrating electric welding.

On the board: a poster indicating the stages of the class

Lesson progress

Organizational moment

Good afternoon, students. I welcome you to today’s physics lesson, which I, Elena Nikolaevna Luneva, will teach, and you will help me with this. The topic of our lesson is “The phenomenon of electromagnetic induction.” Please write down the topic of the lesson in your notebook. State the goals and objectives of the lesson. Our lesson will be held under the motto: “Remember - look - draw conclusions - share ideas.” On your tables there are cards with pictures of little people, which we will use at the end of the lesson.

Reflection: they looked at each other and smiled, looking into each other’s eyes.

Work on the topic of the lesson

Motivation and updating of knowledge.

1. The figure shows three points: A, M, N. In which of them will the magnetic field of the current flowing through the conductor BC act on the magnetic needle with the greatest force, with the least force?

2. A current of the indicated direction is passed through a coil, inside of which there is a steel rod. Determine the poles of the resulting electromagnet. How can you change the position of the poles of this electromagnet?

3. The figure shows two bare conductors connected to a current source and a lightweight aluminum tube AB. Determine the direction of the current in the tube AB if, as a result of the interaction of this current with the magnetic field, the tube rolls along the conductors in the direction indicated in the figure. Which pole of the current source is positive and which is negative?

4. The figure shows a wire circuit placed in a uniform magnetic field. At what orientation of the circuit in relation to the magnetic induction lines is the magnetic flux penetrating the area of ​​this circuit maximum and equal to zero?

5.Explain Oersted's experiment.

Statement of the problem.

1820 Oersted concluded: “Electricity gives rise to magnetism.”

What do you think: “Can magnetism generate electricity”?

Many scientists tried to solve this problem at the beginning of the 19th century. The English scientist M. Faraday also put it before himself. In 1822 He wrote in his diary “Convert magnetism into electricity.”

What needs to be done to obtain an electric current from a magnetic field?

Listen to students' statements.

It took M. Faraday almost 10 years to solve it.

Faraday's experiment: a coil connected to a galvanometer, a magnet is brought closer to this coil and removed.

What do you observe as the magnet approaches the coil?

Why did the needle deviate?

The magnet is in the coil, what do you see?

Why didn't the needle deviate?

We remove the magnet from the coil, what do we observe? Why did the arrow deviate? In which direction did the arrow deviate?

Why does current occur in the coil?

Is it possible to change the current value?

How? What needs to be done for this?

What conclusion can be drawn from this experience?

Conclusion: Electric current arises when the number of magnetic induction lines penetrating a closed circuit changes.

We have considered only one way of generating electric current. There are several other ways to generate electric current. And now you and I will work in groups and solve experimental problems.

Work in groups.

Group 1: strip magnet, connecting wires, milliammeter, coil.

Task: Bring the magnet closer to the coil and move the magnet away from the coil.

What are you observing?

Why did electric current arise?

What will happen if you attach a magnet and start moving the coil relative to the magnet?

Group 2: current source, two coils (one is inserted into the other), connecting wires, milliammeter, key.

Lock the key. Move one coil relative to another coil. What are you observing?

Close and open the key and watch what happens?

Why did electric current occur in the circuit?

Draw a conclusion from your experiments.

Group 3: current source, rheostat, 2 coils with an iron core, connecting wires, milliammeter.

Slowly move the rheostat slider and observe whether an electric current will appear in the circuit?

Why does electric current occur?

Now move the rheostat slider faster. What can you say about the current value?

Draw a conclusion from your experiments.

Group 4: two magnets fixed in stands, a wire frame, connecting wires, a milliammeter.

Rotate the frame slowly between the poles of the magnet. What will happen?

At what moments does the milliammeter needle deviate?

Why does current appear and then disappear in the frame?

Draw a conclusion from your experience.

Discussion of the experiment results

Methods for producing electric current.

Movement of a magnet relative to a coil;

Movement of the coil relative to the magnet;

Closing and opening the circuit;

Rotation of the frame inside the magnet;

Moving the rheostat slider;

The movement of one coil relative to another.

This current is called induction; its name indicates only the cause of the current.

Causes of electric current.

1. When changing the magnetic flux penetrating the area covered by the conductor;

2. By changing the current in the circuit;

3. By changing the orientation of the circuit relative to the lines of magnetic induction.

Guys, let's draw a general conclusion from the demonstrated experiments.

Conclusion: In a closed circuit that is placed in an alternating magnetic field, an electric current arises if and only if the number of lines of force penetrating the circuit changes.

The phenomenon that we discussed is called electromagnetic induction.

Definition: The phenomenon of electromagnetic induction is the occurrence of an induced current in a conducting circuit, which is either at rest in a time-varying magnetic field or moving in a constant magnetic field, such that the number of magnetic induction lines penetrating the circuit changes.

4. Application of electromagnetic induction.

The discovery of electromagnetic induction is one of the most remarkable scientific achievements of the first half of the 19th century. It caused the emergence and rapid development of electrical engineering and radio engineering. Electromagnetic induction is used in modern technology: metal detectors, electrodynamic microphones, in magnetic levitation trains, in household microwave ovens, reading video and audio information from magnetic tapes.

Faraday was the first to construct an imperfect model of an electric current generator that converts mechanical rotational energy into current, consisting of a copper disk rotating between the poles of a strong magnet. The current recorded by the galvanometer was weak, but the most important thing was done: the principle of constructing a current generator was found. You will study the design and principle of operation of the generator in the next lesson.

Electromagnetic induction is used in various technical devices and instruments. Let's consider such a device - a transformer.

A transformer is a device used to increase or decrease alternating voltage.

Transformer structure: magneto - soft steel core, on which two coils with wire windings are placed. The primary winding is connected to an alternating voltage source, the secondary winding is connected to the load.

Experience: 1. Connect a light bulb to the secondary winding of the transformer. Show how the light bulb lights up when we remove the core connecting the windings and when we short the coils with the core.

What are you observing? Why does the light bulb burn weaker in the first case than in the second case?

2. Remove the secondary coil from the transformer and instead of this coil, put and remove a wire coil on the rod, first without a core.

What are you observing?

Then close the circuit with the core.

What are you observing? Why does the light bulb burn brighter?

3. Instead of the second coil, we use a device to demonstrate welding. Show how a spark appears and how the electrodes melt.

Consolidation of the studied material.

What did we learn in today's lesson?

What is the phenomenon of electromagnetic induction?

What conditions are necessary for the existence of the phenomenon of electromagnetic induction?

In what ways can induced current be obtained?

What determines the magnitude of the induction current?

Summing up. Homework.

1. § 49, exercise 39

2. Design creative works

Summary of an open lesson in physics in 9th grade.

"Electromagnetic induction".

Lesson objectives:

Educational:study the physical features of the phenomenon of electromagnetic induction, formulate the concepts: electromagnetic induction, induced current.

developing: to develop in students the ability to highlight the main and essential things in material presented in different ways, to develop the cognitive interests and abilities of schoolchildren in identifying the essence of processes.

educational: cultivate diligence, accuracy and clarity when answering, the ability to see physics around you.

Lesson Objectives

Educational:

1. study the phenomenon of electromagnetic induction and the conditions for its occurrence;
2. consider the history of the issue of the connection between the magnetic field and the electric field;
3. show cause-and-effect relationships when observing the phenomenon of electromagnetic induction,
4. promote the actualization, consolidation and generalization of acquired knowledge, and the independent construction of new knowledge.

Educational: contribute to the development of the ability to work in a group, express one’s own judgments and argue one’s point of view.

Educational:

1. promote the development of students' cognitive interests;
2. promote the modeling of your own value system based on the idea of ​​self-development.

Progress of the lesson.

1. Org. Moment.

Today in class we continue to study magnetic phenomena. We will get acquainted with a new phenomenon that underlies the operation of alternating current sources. But first we need to remember the basic concepts that we will need.

Checking the assimilation of previously studied material

differentiated task (option 1 – test; option 2 – table)

After completing the task, students change tasks for checking.

1 option

1. A magnetic field exists... (choose the correct answers)

a) around a conductor carrying current
b) around moving charged particles
c) around stationary charges (-)
d) around the magnet

1. Who was the first scientist to prove that a magnetic field exists around a current-carrying conductor?

a) Oersted (+)
b) Newton
c) Archimedes
d) Ohm

1. To increase the magnetic flux (see Figure 1), you need to:

a) replace the aluminum frame with an iron one
b) lift the frame up
c) take a weaker magnet
d) strengthen the magnetic field (+)

Figure 1

1. The conductor shown in Figure 2 is attracted to the magnet because:

a) copper conductor
b) the conductor is acted upon by the Ampere force (+)
b) the conductor is electrified
c) the conductor is loosely tensioned

Figure 2

5. How is the force acting from the magnetic field on a moving electron directed:

E V 4

1) 1 2) 2 3) 3 4) 4

6 . Determine the unknown quantity:L= 1m; B = 0.8 T; I= 20A F - ?

1. Answers 1. a, b, d assessment:
2. 2. and without errors “5”
3. 3. g 1 error "4"
4. 4. b 2 errors “3”
5. 5. 4
6. 6. 16 N

Option 2

Answers:

grade : 1 point for each
correctly filled line

1. Learning new material.

Today we are studying the phenomenon of electromagnetic induction. Let's try to figure out what this phenomenon is and what its significance is.

Until the beginning of the 19th century. humanity knew only chemical sources of current - galvanic elements. The English scientist Michael Faraday was convinced of the existence of a relationship between various natural phenomena. Magnetic and electric fields are related to each other. Email current can cause the appearance of a magnetic field. Couldn't a magnetic field create an electric current? Many scientists tried to solve this problem at the beginning of the 19th century. But the first decisive contribution to the discovery of EM interactions was made by Michael Faraday. After all, it is possible to convert thermal energy into mechanical and vice versa, electrical into chemical and vice versa. Therefore, in his diary in 1822, Michael Faraday wrote: “Convert magnetism into electricity!” ANDI walked towards my goal for ten whole years. As a reminder of what he should always think about, he even carried a magnet in his pocket. And such a relationship was established.

Faraday's experiments. Watching the film.

1. Analysis of the results obtained, conclusions. (Knowledge systematization)

Questions for the film.

What was common in all four of Faraday's experiments?

1. When does current occur in the coil?

2. What determines the direction of the induction current?

3. What determines the magnitude of the induction current?

4. What is the phenomenon of electromagnetic induction?

5. Where and for what can this phenomenon be applied??

1. Primary knowledge control (work in groups)Consolidation of what has been covered

1. Assignment to group 1:By whom, when and how was the EMR phenomenon discovered?
2. Assignment to group 2: How does the EMR phenomenon arise and occur?
3. Assignment to group 3:What is the significance of the EMR phenomenon?

1. Summing up the lesson

Today in class we are with you

1. studied the phenomenon of electromagnetic induction and the conditions for its occurrence;
2. reviewed the history of the issue of the connection between the magnetic field and the electric field;
3. showed cause-and-effect relationships when observing the phenomenon of electromagnetic induction, i.e. turned magnetism into electricity, and now we know that electric current generates a magnetic field, and an alternating magnetic field generates electric current

(Lesson grades)

1. Homework assignment

ξ49, control 39 (1, 2)

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Slide captions:

Open lesson on physics in 9th grade. The phenomenon of electromagnetic induction MOU "Secondary School No. 19" G.O. Elektrostal

Checking the assimilation of previously studied material Select the correct answer options. 1. A magnetic field exists... a) around a conductor with current b) around moving charged particles c) around stationary charges d) around a magnet 2. Who was the first scientist to prove that a magnetic field exists around a conductor with current? a) Oersted b) Newton c) Archimedes d) Ohm

3. To increase the magnetic flux (see Figure 1), you need to: a) replace the aluminum frame with an iron one b) raise the frame up c) take a weaker magnet d) strengthen the magnetic field Figure 1 4. The conductor shown in Figure 2 is attracted to magnet, because: a) the conductor is copper b) the Ampere force acts on the conductor b) the conductor is electrified c) the conductor is weakly tensioned Figure 2

5. What is the direction of the force acting from the magnetic field on a moving electron: 3 V 2 1 e V 4 1) 1 2) 2 3) 3 4) 4 6. Determine the unknown quantity: L = 1m; B = 0.8 T; I = 20 A F - ?

Fill out the table Electrostatic field Magnetic field Vortex electric field Source of the field What serves as an indicator of the field? Potential or vortex? Are the field lines closed or open?

Answers: 1. a, b, d rating: 2. a without errors “5” 3. d 1 error “4” 4. b 2 errors “3” 5. 4 6. 16 N

Answers: 1 point for each correctly filled line Electrostatic field Magnetic field Vortex electric field Field source Electric charges Moving charges - current Changing magnetic field What serves as an indicator of the field? Electric charges Moving charges Electric charges Potential or vortex? Potential Vortex Vortex Are the field lines closed or open? Not closed, starts and ends on charges Closed Closed

Studying a new topic Michael Faraday (09.22.1791 - 08.25.1867) 1821 - “Convert magnetism into electricity” August 29, 1831 - discovery of the phenomenon of electromagnetic induction

Faraday's experiments Induction current is a current that arises in a coil when a permanent magnet moves relative to it

Questions for the film: 1. When does current occur in the coil? 2. What determines the direction of the induction current? 3. What determines the magnitude of the induction current? 4. What is the phenomenon of electromagnetic induction? 5. Where and for what can this phenomenon be applied? ? Movie

Electromagnetic induction is the phenomenon of the appearance of an induced current in a coil with any change in the magnetic field penetrating the area of ​​its turns.

Electric current generator This is a device in which mechanical energy is converted into electrical energy

Consolidation of what has been learned Work in groups. Group I Who, when and how was the EMR phenomenon discovered? Group II How does the EMR phenomenon arise and occur? Group III What is the significance of the EMR phenomenon?

Today in class: we studied the phenomenon of electromagnetic induction and the conditions for its occurrence; reviewed the history of the issue of the connection between the magnetic field and the electric field; showed cause-and-effect relationships when observing the phenomenon of electromagnetic induction, i.e. turned magnetism into electricity, and now we know: electric current generates a magnetic field, and an alternating magnetic field generates electric current.

Homework § 49, exercise 39 (1, 2) orally.

conclusion Comprehensive studies of EMR have shown that with the help of this phenomenon it is possible to obtain an electric current of any power, which allows the widespread use of electricity in industry. Now almost all electrical energy used in industry is obtained using induction generators, the operating principle of which is based on the EMR phenomenon.

Therefore, Faraday is rightfully considered one of the founders of electrical engineering.

Summary lesson:

"Electromagnetic

induction"

Kholmogorova A.A.

Application.

1.

5. Summing up.

Reflection.

1. Did you like the lesson?

2.What moments of the lesson do you find most interesting?

3.What difficulties did you experience in the lesson?

4.Comments and suggestions for the future.

Download:

Preview:

Open lesson on physics in 11th grade.

Summary lesson:

"Electromagnetic

induction"

Developed by a physics teacher at Sokolchinsky Secondary School No. 3

Kholmogorova A.A.

Organizational structure of the lesson.

Application.

1. In the electromagnetic induction section, open a window showing a diagram of the movement of a conductor in a uniform magnetic field.

Press the start button. Observe how the magnetic flux changes and how long it took for this change to occur. Write down the formula for calculating the induced emf. Calculate the emf and compare the result with the data.

In this figure, determine the direction of the induction current and write it down.

2. Open the window of the Faraday experiment model1.

Lower and raise the magnet, first slowly and then quickly. Do the same with the coil. In which case does the magnetic flux change faster? Draw a conclusion.

3. Open the window of the Faraday experiment model2. Consider the model.

How does the current change when the primary winding closes and opens? Why is there a short current pulse in the indicator coil?

4. Open the test from the “Electromagnetic induction” section. Write down the answers to the questions in your notebook, and do the necessary calculations in your notebook. Justify your answers.

5. Summing up.

Answer the following questions:

Reflection.

1. Did you like the lesson?

2.What moments of the lesson do you find most interesting?

3.What difficulties did you experience in the lesson?

4.Comments and suggestions for the future.