Plan - summary of a lesson in physics in grade 8 on the topic:

The magnetic field of a coil with current. Electromagnets.

Laboratory work No. 8 "Assembling an electromagnet and testing its operation."

Lesson Objectives: teach how to assemble an electromagnet from finished parts and experimentally check what its magnetic effect depends on.

Tasks.

Educational:

1. using the game form of activity in the lesson, repeat the basic concepts of the topic: magnetic field, its features, sources, graphic image.

2. organize activities in pairs of permanent and replaceable composition for the assembly of an electromagnet.

3. create organizational conditions for conducting an experiment to determine the dependence of the magnetic properties of a current-carrying conductor.

Developing:

1. develop students' skills of effective thinking: the ability to highlight the main thing in the material being studied, the ability to compare the facts and processes being studied, the ability to logically express their thoughts.

2. develop skills in working with physical equipment.

3. to develop the emotional-volitional sphere of students in solving problems of varying degrees of complexity.

Educational:

1. create conditions for the formation of such qualities as respect, independence and patience.

2. to promote the formation of a positive "I - competence".

Cognitive. Identify and formulate a cognitive goal. Build logical chains of reasoning.

Regulatory. They set a learning task based on the correlation of what has already been learned and what is still unknown.

Communicative. Share knowledge among group members to make effective joint decisions.

Personal. O conscious, respectful and benevolent attitude towards another person, his opinion.

Lesson type: methodological lesson.

Problem-Based Learning Technology and CSR.

Equipment for laboratory work: collapsible electromagnet with parts (intended for frontal laboratory work on electricity and magnetism), current source, rheostat, key, connecting wires, compass.

Demos:

Structure and course of the lesson.

1. Repeat the basic concepts of the topic. Entrance testing.

Game "Continue the offer."

Substances that attract iron objects are called ... (magnets).

Interaction of a conductor with current and a magnetic needle
first discovered by a Danish scientist ... (Oersted).

Interaction forces arise between conductors with current, which are called ... (magnetic).

The places of the magnet, in which the magnetic effect is most pronounced, are called ... (magnet poles).

Around a conductor with electric current there is ...
(a magnetic field).

The source of the magnetic field is ... (a moving charge).

7. Lines along which the axes are located in a magnetic field
small magnetic arrows are called ... (magnetic lines of force).

The magnetic field around a conductor with current can be detected, for example, ... (using a magnetic needle or using iron filings).

9. Bodies that retain their magnetization for a long time are called ... (permanent magnets).

10. The same poles of the magnet ..., and the opposite - ... (repel,

are attracted

2. "Black box".

What is hidden in the box? You will find out if you understand what is at stake in the story from Dari's book "Electricity in its applications." Representation of a French magician in Algiers.

“On the stage is a small ironed box with a handle on the lid. I call a stronger person from the audience. In response to my challenge, an Arab of medium height, but strong build, came forward ...

- Approach the court, - I said, - and lift the box. The Arab bent down, picked up the box and arrogantly asked:

- Nothing else?

“Wait a little,” I replied.

Then, assuming a serious air, I made an imperious gesture and said in a solemn tone:

- You are now weaker than a woman. Try lifting the box again.

The strong man, not at all afraid of my charms, again took hold of the box, but this time the box resisted and, despite the desperate efforts of the Arab, remained motionless, as if chained to the place. The Arab tries to lift the box with enough force to lift a huge weight, but all in vain. Tired, out of breath and burning with shame, he finally stops. Now he's starting to believe in the power of sorcery."

(From the book of Ya.I. Perelman "Entertaining physics. Part 2".)

Question. What is the secret of sorcery?

Discuss. Express their position. From the "Black Box" I take out a coil, iron filings and a galvanic cell.

Demos:

1) the action of a solenoid (a coil without a core), through which a direct current flows, on a magnetic needle;

2) the action of the solenoid (coil with a core), through which a direct current flows, on the armature;

3) attraction of iron filings by a coil with a core.

They conclude what an electromagnet is and formulate the purpose and objectives of the lesson.

3. Performing laboratory work.

A coil with an iron core inside is called electromagnet. An electromagnet is one of the main parts of many technical devices. I suggest you assemble an electromagnet and determine what its magnetic effect will depend on.

Lab #8

"Assembling an electromagnet and testing its operation"

The purpose of the work: to assemble an electromagnet from finished parts and to test by experience what its magnetic action depends on.

Instructions for work

Task number 1. Make an electrical circuit from a battery, a coil, a key, connecting everything in series. Close the circuit and use the compass to determine the magnetic poles of the coil. Move the compass along the axis of the coil to a distance at which the effect of the magnetic field of the coil on the compass needle is negligible. Insert the iron core into the coil and observe the effect of the electromagnet on the needle. Make a conclusion.

Task number 2. Take two coils with an iron core, but with a different number of turns. Check the poles with a compass. Determine the effect of electromagnets on the arrow. Compare and draw a conclusion.

Task number 3. Insert the iron core into the coil and observe the action of the electromagnet on the arrow. Use the rheostat to change the current in the circuit and observe the effect of the electromagnet on the arrow. Make a conclusion.

They work in static pairs.

1 row - task number 1; 2 row - task number 2; 3 row - task number 3.

Work in pairs of shifts.

1 row - task number 3; 2 row - task number 1; 3 row - task number 2.

1 row - task number 2; 2 row - task number 3; 3 row - task number 1.

At the end of the experiments, conclusions:

1. if an electric current passes through the coil, then the coil becomes a magnet;

2.The magnetic action of the coil can be strengthened or weakened:
a. changing the number of turns of the coil;

b. changing the strength of the current passing through the coil;

v. introducing an iron or steel core into the coil.

Self-training sheet, self-assessment.

1. Entrance testing. Game "Continue the offer."

1.__________________________

2.__________________________

3.__________________________

4.__________________________

5.__________________________

6.__________________________

7.__________________________

8.__________________________

9.__________________________

10._________________________

2. Laboratory work No. 8 "Assembling an electromagnet and testing its operation"

The purpose of the work: to assemble _______________ from finished parts and to verify by experience what _____________ action depends on.

Devices and materials: a galvanic cell, a rheostat, a key, connecting wires, a compass, parts for assembling an electromagnet.

Progress.

Task number 1.

Task number 2.

Task number 3.

Topic: Assembling the electromagnet and testing its operation.

Objective: assemble an electromagnet from ready-made parts and test its magnetic effect by experience.

Equipment:

• current source (battery or accumulator);
• rheostat;
• key;
• connecting wires;
• compass;
• parts for assembling an electromagnet.

Instructions for work

1. Make an electrical circuit from a current source, a coil, a rheostat and a key, connecting everything in series. Close the circuit and use the compass to determine the magnetic poles of the coil.

2. Move the compass along the axis of the coil to such a distance that the effect of the magnetic field of the coil on the compass needle is negligible. Insert the iron core into the coil and observe the effect of the electromagnet on the needle. Make a conclusion.

3. Use the rheostat to change the current in the circuit and observe the effect of the electromagnet on the arrow. Make a conclusion.

4. Assemble the arc magnet from the prefabricated parts. Connect the coils of an electromagnet to each other in series so that opposite magnetic poles are obtained at their free ends. Check the poles with a compass. Use a compass to determine where the north and where is the south pole of the magnet.

Lab No. 8 _____________________

the date

Assembling the electromagnet and testing its operation.

Target: assemble an electromagnet from ready-made parts and test by experience what its magnetic effect depends on.

Equipment: power supply, rheostat, key, connecting wires, compass (magnetic needle), arcuate magnet, ammeter, ruler, parts for assembling an electromagnet (coil and core).

Safety regulations.Read the rules carefully and sign that you agree to follow them..

Carefully! Electricity! Make sure that the insulation of the conductors is not broken. When conducting experiments with magnetic fields, you should take off your watch and put away your mobile phone.

I have read the rules and agree to abide by them. ________________________

Student Signature

Progress.

1. Make up an electrical circuit from a power source, a coil, a rheostat, an ammeter and a key, connecting them in series. Draw a circuit assembly diagram.

1. Close the circuit and use the magnetic needle to determine the poles of the coil.

Measure the distance from the coil to the needle L 1 and current I 1 in the coil.

Record the measurement results in table 1.

1. Move the magnetic needle along the axis of the coil to such a distance L2,

on which the effect of the magnetic field of the coil on the magnetic needle is negligible. Measure this distance and current I 2 in a coil. Also record the measurement results in Table 1.

Table 1

4. Insert the iron core into the coil and observe the action

Electromagnet on the arrow. measure distance L 3 from the coil to the arrow and

Current strength I 3 in a core coil. Record the measurement results in

Table 2.

1. Move the magnetic needle along the axis of the core coil to

Distance L 4 , on which the action of the magnetic field of the coil on the magnetic

Arrow slightly. Measure this distance and current I 4 in the coil.

Also record the measurement results in table 2.

table 2

1. Compare the results obtained in paragraph 3 and paragraph 4. Do conclusion: ______________

____________________________________________________________________

1. Use a rheostat to change the current in the circuit and observe the effect

Electromagnet on the arrow. Do conclusion: _____________________________

____________________________________________________________________

____________________________________________________________________

1. Assemble the arcuate magnet from prefabricated parts. Electromagnet coils

connect together in series so that opposite magnetic poles are obtained at their free ends. Check the poles with a compass, determine where the north and where is the south pole of the electromagnet. Sketch the magnetic field of the electromagnet you received.

TEST QUESTIONS:

1. What is the similarity between a coil with current and a magnetic needle? __________ ________________________________________________________________________________________________________________________________

1. Why does the magnetic effect of a coil carrying current increase if an iron core is introduced into it? ___________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________

1. What is an electromagnet? For what purposes are electromagnets used (3-5 examples)? ________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________

1. Is it possible to connect the coils of a horseshoe electromagnet so that the ends of the coil have the same poles? ________________________
   ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1. What pole will appear at the pointed end of an iron nail if the south pole of a magnet is brought near its head? Explain the phenomenon ___________ __________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Equipment: power supply, rheostat, key, connecting wires, compass (magnetic needle), arcuate magnet, ammeter, ruler, parts for assembling an electromagnet (coil and core).
Safety regulations. Read the rules carefully and sign that you agree to follow them. .

Carefully! Electricity! Make sure that the insulation of the conductors is not broken. When conducting experiments with magnetic fields, you should take off your watch and put away your mobile phone.

I have read the rules and agree to abide by them. ________________________

Student Signature

Progress.

1. 
   Compose electrical, coil, rheostat, ammeter and key by connecting them in series. Draw a circuit assembly diagram.

Electrical circuit assembly diagram

1. 
   Close the circuit and use the magnetic needle to determine the poles of the coil.

Record the measurement results in table 1.

16

1. 
   Move the magnetic needle along the axis of the coil to such a distanceL2 ,

Table 1

4. Insert the iron core into the coil and observe the action

electromagnet on the arrow. measure distanceL3 from the coil to the arrow and

current strengthI3 in a core coil. Record the measurement results in

table 2.

1. 
   Move the magnetic needle along the axis of the core coil to

arrow slightly. Measure this distance and currentI4 in a coil.

Also record the measurement results in table 2.

table 2

1. 
   Compare the results obtained in paragraph 3 and paragraph 4. Doconclusion: ______________

1. 
   Use a rheostat to change the current in the circuit and observe the effect

____________________________________________________________________

____________________________________________________________________

1. 
   Assemble the arcuate magnet from prefabricated parts. Electromagnet coils

17

TEST QUESTIONS:

What is the similarity between a coil with current and a magnetic needle? __________ ________________________________________________________________________________________________________________________________

1. 
   Why coil magnetic action, through which the current flows, is amplified if an iron core is introduced into it? ___________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________

1. 
   What is an electromagnet? For what purposes are electromagnets used (3-5 examples)? ________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________

1. 
   Is it possible to connect horseshoe coils electromagnet so so that the ends of the coil have the same poles? ________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1. 
   What pole will appear at the pointed end of an iron nail if the south pole of a magnet is brought near its head? Explain the phenomenon ___________ __________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________