Permanent magnets. are attracted by a magnet, which is bad

Lesson topic: " Permanent magnets. Earth's magnetic field."

Physics teacher

MBOU secondary school No. 27

Guselnikova Olga Viktorovna

O. Continue studying magnetic phenomena.
R. Continue developing the skills to explain observed phenomena, conduct experiments, analyze their results, and draw conclusions.
B. Development of group interaction skills and dialogue skills.

Know:

Be able to

Scientific facts: attraction of iron-containing substances by magnets, attraction and repulsion of magnets, influence of external magnetic field enhances magnetic properties, studying the magnetic field pattern using iron filings
Concepts: permanent magnets, pole magnets

Apply knowledge to explain phenomena related to the existence of the magnetic field of a magnet.

Multimedia projector, computer, bar and arc magnets, cardboard, metal filings, paper clips, iron nail, steel blade, paper, pencil, steel knitting needle, two magnetic needles, magnet and magnetic needle.

Warm-up 1. The magnetic needle has two poles... and...

2. A magnetic field exists around any current-carrying conductor, i.e. around …

electrical

charges.

3. Around stationary electric charges there is only... a field.

4 . There are ... and ... fields around moving charges.

5. The iron introduced inside the coil … magnetic action coils .

6 . Coil With magnetic the core inside is called …

7. What materials can a magnetic needle be made from: copper, iron, glass, wood, steel?

What is the poem about?

A piece of iron with unchanging strength Another piece of iron attracts But this power is not wingless peace, Only tireless experience strengthens.

I. Franko

Permanent magnets - these are bodies that long time retain magnetization.

Pole - the place of the magnet where the strongest effect is detected.

N – north pole of the magnet

S – south pole of the magnet

Strip magnet

Arc magnet

Artificial magnets - These are magnets created by man.

Natural (or natural) magnets - these are pieces of magnetic iron ore (iron ore).

They are made from:

steel,
nickel,
cobalt

It is impossible to obtain a magnet with one pole. If a magnet is divided into two parts, then each of them will turn out to be a magnet with two poles.

№ 1

№ 2

Experimental task. Task No. 1.

Equipment: metal clips,

magnets.

1 . Take a magnet, place a paperclip exactly

to the middle of the magnet, where the boundary between

red and blue halves. Does it attract

magnet paperclip?

2. Bring paper clips closer to different places on the magnet,

starting from the middle and moving towards the ends.

Which places does the magnet detect the most?

strong magnetic effect?

Equipment: iron nail, steel blade, copper, aluminum, paper, pencil, plastic, magnet.

You have various items on the table.

Determine which substances are good

are attracted by a magnet, which is bad,

which ones are not attracted at all.

Enter the results in the table.

Task No. 2

Strongly

attracts

Weakly attracts

attracts

Task No. 3.

Equipment: magnet, paper clips, steel knitting needle.

1. Check the magnetic property of the knitting needle by holding it close to the paper clips. Does the knitting needle attract paper clips?

2. Place the knitting needle on the table and rub it firmly with one of the ends of the magnet. Rub in one direction only

(make 15-20 movements), and then carry the magnet back through the air. Check the magnetic property of the spoke again. Does steel become magnetic when in contact with a magnet?

Task No. 4.

Equipment: two magnetic needles.

1. Bring a magnetic needle closer to another

with the same arrow, first with red ends and then with blue ends.

How do arrows interact?

2. Bring the red end of one arrow closer to the blue end of the other. How do the arrows interact?

Based on the experiments performed, draw a general conclusion.

Task No. 5.

Equipment: magnet and magnetic needle.

1. Apply to the blue and then to the red end

magnetic needle magnet. What can I say

about the interaction of a magnetic needle and a magnet?

2. Make drawings in your notebook and sign them

under them, in which case the magnetic needle

is attracted, and in which it is repelled.

Task No. 6.

Equipment: arc magnet, cardboard, iron filings.

1. Take an arc magnet. Place cardboard on top of it.

Sprinkle iron filings onto the cardboard and shake them by lightly tapping the cardboard with your finger.

2. Draw a picture of the magnetic lines of force in your notebook. Are the magnetic field lines of a permanent magnet closed?

How is the magnetic needle located in given point magnetic field?

Earth's magnetic field

SCIENTISTS ARE PIONEERS IN THE STUDY OF EARTH MAGNETISM

William Gilbert ( 1544 –1603 ) – a pioneer in the study of the Earth's magnetic field

W. Gilbert assumed that the Earth is a large magnet. To confirm this assumption, Hilbert performed a special experiment. He carved a large ball from a natural magnet. By bringing the magnetic needle closer to the surface of the ball, he showed that it is always set in a certain position, just like the compass needle on Earth.
W. Gilbert described methods for magnetizing iron and steel. Gilbert's book came first scientific research magnetic phenomena.

In 1600 English doctor G.H. Gilbert brought out basic properties permanent magnets.

1. Opposite magnetic poles attract, like magnetic poles repel.

2. Magnetic lines – closed lines. Outside the magnet, magnetic lines leave "N" and enter "S", closing inside the magnet.

A.M.Amp ( 1775 - 1836) - great French scientist.

In 1820, A. Ampere suggested that magnetic phenomena caused by interaction electric currents. Each magnet is a system of closed electric currents, the planes of which are perpendicular to the axis of the magnet. The interaction of magnets, their attraction and repulsion, is explained by the attraction and repulsion existing between currents. Terrestrial magnetism is also caused by electric currents that flow in globe. This hypothesis required experimental confirmation, and Ampere carried out a whole series of experiments to substantiate it.

Ampere's hypothesis

Ampere (1775-1836) hypothesized the existence of electric currents circulating inside each molecule of a substance. In 1897 The hypothesis was confirmed by the English scientist Thomson, and in 1910. The currents were measured by the American scientist Millikan.

Conclusion: the movement of electrons is circular current, and we know from previous lessons that there is a magnetic field around a conductor carrying electric current

Earth's magnetic field.

The Earth's South Magnetic Pole is approximately 2100 km away from the North Geographic Pole.
The Earth's North Magnetic Pole is located near the South geographic pole, namely at 66.5 degrees. Yu.Sh. and 140 degrees. East longitude.

Earth's magnetic poles

The Earth's magnetic poles have changed places (reversals) many times. This has happened 7 times in the last million years.

570 years ago, the Earth's magnetic poles were located near the equator.

Test

1. When electric charges are at rest, then around them is found...

A. magnetic field;

B. electric field;

IN. electric and magnetic field.

Test

2. The magnetic field lines of a conductor carrying current are...

A. closed curves enclosing a conductor;

B. circles;

IN. straight lines.

Test

3. Which of the following metals is more strongly attracted by a magnet?

A.- aluminum.

B.- iron.

IN.- copper.

Test

4 . At ... current strength, the effect of the magnetic field of the current coil is ....

A.- increase; intensifies.

B.-increase; weakens.

IN.- decrease; intensifies.

Test

5. Same name magnetic poles..., different names...

A. are attracted; repulse;

B. push off; are attracted.

Test

6. Is it possible to make a magnet with one pole?

A. Yes, you can
B. No, you can't

Answers to the test task.

Homework

Paragraphs 59-60
Questions for paragraphs
Messages, presentations:

"Compass, the story of its discovery"

"Magnetic fields in the Solar System"

Permanent magnets

The stone that attracts iron, described above by ancient scientists, is a so-called natural magnet, found quite often in nature. It is a widespread mineral with a composition of 31% FeO and 69% Fe2O3, containing 72.4% iron. It is also called magnetic iron ore, or magnetite.

If you cut a strip from such material and hang it on a thread, then it will be installed in space in a very specific way: along a straight line running from north to south. If you remove the strip from this state, that is, deviate it from the direction in which it was, and then again leave it to itself, then the strip, having made several oscillations, will take its previous position, settling in the direction from north to south (Fig. 2) .

https://pandia.ru/text/78/405/images/image002_96.jpg" align="left" width="196" height="147 src=">If you immerse this strip in iron filings, they will be attracted to the strip is not the same everywhere. The greatest force of attraction will be at the ends of the strip, which were facing north and south.
These are the places where the stripes are found greatest strength attractions are called magnetic poles.

The pole pointing north is called the north pole of the magnet (or positive) and is designated by the letter N (or C); southward pole"
called the south pole (or negative) and is designated by the letter S (or Yu).
The interaction of the poles of a magnet can be studied as follows. Let's take two strips of magnetite and hang one of them on a thread, as already mentioned above. Holding the second strip in your hand, we will bring it to the first with different poles.

https://pandia.ru/text/78/405/images/image004_53.jpg" align="left" width="183" height="136 src=">It turns out that if, to north pole If one strip brings the south pole of the other closer, then attractive forces will arise between the poles, and the strip suspended on the thread will be attracted. If a second strip is also brought to the north pole of a suspended strip with its north pole, then the suspended strip will be repelled.

Instead of strips, let’s take a demonstration magnet and plexiglass panels with metal filings inside. Let's see what the magnetic field lines of two interacting magnets look like. By carrying out such experiments, one can be convinced of the validity of the law established by Hilbert about the interaction of magnetic poles: like poles repel, unlike poles attract.

Using a simple device we can view the spectra of magnetic fields.

If we wanted to divide the magnet in half in order to separate the north magnetic pole from the south, it turns out that we would not be able to do this. By cutting a magnet in half, we get two magnets, each with two poles. If we continued this process further, then, as experience shows, we would never be able to obtain a magnet with one pole (Fig. 3). This experience convinces us that the poles of a magnet do not exist separately, just as negative and positive electric charges exist separately. Consequently, the elementary carriers of magnetism, or, as they are called, elementary magnets, must also have two poles.

https://pandia.ru/text/78/405/images/image006_39.jpg" alt="Fig." align="left alt="width="100" height="47"> Описанные выше естественные магниты в. настоящее время практически не используются. Гораздо более сильными и более удобными оказываются искусственные !} permanent magnets. The easiest way to make a permanent artificial magnet is from a steel strip, if you rub it from the center to the ends with the opposite poles of natural or other artificial magnets (Fig. 3). Strip-shaped magnets are called strip magnets. It is often more convenient to use a magnet shaped like a horseshoe. This type of magnet is called a horseshoe magnet.

Artificial magnets are usually made in such a way that opposite magnetic poles are created at their ends. However, this is not at all necessary. It is possible to make a magnet in which both ends will have the same pole, for example, the north one. You can make such a magnet by rubbing a steel strip with equal poles from the middle to the ends.

https://pandia.ru/text/78/405/images/image008_35.jpg" align="left" width="190" height="142 src=">

However, the north and south poles of such a magnet are inseparable. Indeed, if you immerse it in sawdust, they will be strongly attracted not only to the edges of the magnet, but also to its middle. It is easy to check that the north poles are located at the edges, and the south pole is in the middle.

Observations of the magnetic effects of current led, back in the first half of the last century, the French physicist Ampere to the idea that a special magnetic field not caused by electric currents does not exist at all. According to Ampere's hypothesis, the magnetic properties of a substance are due to special molecular currents flowing inside the molecules of the substance. These closed molecular currents are, according to Ampere, a kind of elementary magnets.

Until our knowledge of the structure of atoms became sufficiently complete, Ampère's hypothesis did not exist. solid support underneath. When it was established that the atom consists of a positively charged nucleus and electrons rotating around it, it was natural to assume that the electrons moving around the nucleus represent the very elementary currents that are the elementary carriers of magnetism. An electron rotating in an orbit around a nucleus has a certain magnetic moment and is an elementary magnet.

As a result

Study of magnetic field spectra

1. The magnet has various parts different attractive force; at the poles this force is most noticeable.

2. A magnet has two poles: north and south, they differ in their properties.

3. Opposite poles attract, like poles repel.

4. A magnet suspended on a thread is positioned in a certain way in space, indicating north and south.

5. It is impossible to obtain a magnet with one pole.

Now there are almost no people left who will gratefully shake your hand for telling you that the Earth is round, saying: “Thank you, friend, I’ll always hear something new from you.”

But why is she spinning? This question baffles not only schoolchildren. Their learned fathers also become thoughtful when the eternal rotation gives them this “why.” “Probably magnetism,” they say.

So why? But... first about magnetism in general.

ELECTROMAGNETIC FIELD FROM A NAIL AND FILE

You can use a file or even a simple nail. obtain clearly visible magnetic fields. It is enough to wrap them with an insulated wire and run a current through it. The electric current, passing through the turns, will create a field, and the core will sharply strengthen it. The core itself of such a simple solenoid, be it a nail or a file, will become a magnet. But at the same time, a magnet core made from a nail will have a fundamental difference from a magnet made from a file. What do you think makes this difference?

This will be discussed below. But if you want to find the difference yourself, then do the following experiments.

Wind an insulated wire 0.1-0.4 mm thick around an ordinary nail. Attach one end of the winding to the flashlight battery (Fig. 1). Place small carnations on the table. Place the head of the nail against the small studs, then attach the other end of the winding to the battery. Small nails will instantly stick to the head of the core nail. When turned off, the carnation batteries will immediately drop.

Now let's make an artificial magnet from a file. Using an emery wheel, grind off the notch from the planes of the file and cut off the required strip from it. Then the strip must be rubbed from the center to the ends - with opposite poles of the magnets. A rigid steel strip can be artificially magnetized in another way - using a constant electric current. Wind a well-insulated wire onto a steel plate, and then turn on the winding through the rheostat for a few seconds.

Now the difference between a magnetized nail and a file will become obvious. In the first case, the core has magnetic properties only during the passage of current (through the turns); in the second case, a permanent magnet is obtained. A file, unlike a nail, will have residual magnetism.

The reason lies in the high hardness of the file material. In a solid steel plate, the atoms that make it up are oriented in a very “strong” way. Therefore, they retain their magnetic properties better.

By cutting a magnet in half, we get two identical magnets with different poles. By repeating this operation, we again obtain magnets with different poles. If we were to cut a magnet into microscopic particles, each of those particles would still have two poles: north (positive) and south (negative).

This fact leads to the conclusion that the poles of a magnet do not exist separately, just as negative (electrons) and positive (protons) electrically charged particles exist. However, it is possible to make a magnet with equal poles at the ends. You just need to rub the steel plate with the same poles, for example the north ones, leading them from the middle to the ends. Then the atoms will be arranged in the structure of the plate so that the north poles will go in one direction, and the south poles in the other.

The magnetic needle is located along the magnetic lines of force. The configuration of magnetic field lines can be easily captured using iron filings. Place the glass with metal filings on the strip magnet and lightly tap the glass. Each magnetized iron particle will represent a small magnetic arrow. Stretching along power lines fields, they will reveal its configuration.

While shaking most sawdust will move to the poles. The equatorial part of the field will thin out. But electrically charged particles behave completely differently.

If negatively and positively charged particles could be sprinkled like sawdust on glass, then the charged particles would be repelled from the poles and concentrated in the equatorial zone of the magnetic field - in the form of a ring. But how can you see all this?

HOMEMADE GALAXIES - WITH A WIVE OF YOUR HAND

Beams of charged particles, in particular electrons (beta particles), are produced in betatrons. In them, electrons are accelerated almost to the speed of light, and the devices themselves weigh tons, and sometimes hundreds of tons. And yet, almost each of us is able to conduct an experiment with an electron beam using ordinary televisions. After all, in the TV tube it is the electrons that hit the kinescope screen in lines, causing a glow.

Take a stronger permanent magnet and bring its pole to the screen. The image on the screen will turn into a spiral resembling a galaxy. If the image twists to the right, this means that the north pole of the magnet is brought to the screen. The south pole of the magnet forms a spiral twisted to the left.

As the magnet approaches the screen, a dark ring will appear opposite it (if the magnet is cylindrical), and in the very center there will be a light point through which the flow of electrons continues to flow towards the pole. The dark spot shows that the magnetic poles repel electrons, sending them toward the equator of the magnetic field and in orbit around the magnet.

Electrons are repelled by the north and south poles. Therefore, they are concentrated in the equatorial plane of the magnetic field in the form of a fairly flat ring, like the rings of the planet Saturn.

Taking right hand magnet at the end of the north pole, bring its entire plane horizontally to the screen. The image on the screen will bend in an arc - upward above the equator of the magnetic field. Turn the magnet over with its south pole to the right - the image on the screen will bend down.

From these experiments it is clear that electrons rotate in a magnetic field in a counterclockwise orbit when looking at the magnet from the north pole. If we are dealing with positively charged particles, then they, repelling from the poles of the magnet, would go in the direction opposite to the direction of the electrons in the orbit.

What happens if a magnet is placed on bearings and irradiated with a fairly powerful flow of electrons? The magnet will probably begin to rotate: in the flow of electrons - clockwise, in the flow of protons - counterclockwise. The direction of rotation of the magnet will be opposite to the direction of twisting of the charged particles.

Now let’s remember that our Earth is a huge magnet, and that a stream of protons falls onto it from space. Now it is clear why we talked for a long time about magnetism before moving on to the promised explanation of the rotation of our planet.

IN ONE ROUND DANCE

The English scientist W. Gelbert believed that the Earth consists of magnetic stone. Later they decided that the Earth was magnetized from the Sun. Calculations refuted these hypotheses.

They tried to explain the magnetism of the Earth by mass flows in its liquid metal core. However, this hypothesis itself relies on the hypothesis of the liquid core of the Earth. Many scientists believe that the core is solid and not iron at all.

In 1891, the English scientist Schuster, apparently for the first time, tried to explain the magnetism of the Earth by its rotation around its axis. I devoted a lot of work to this hypothesis famous physicist P. N. Lebedev. He assumed that, under the influence of centrifugal force, electrons in atoms are shifted towards the Earth's surface. This causes the surface to be negatively charged, which causes magnetism. But experiments with ring rotation up to 35 thousand revolutions per minute did not confirm the hypothesis - magnetism did not appear in the ring.

In 1947, P. Blacket (England) suggested that the presence of a magnetic field in rotating bodies is an unknown law of nature. Blackett tried to establish the dependence of the magnetic field on the speed of rotation of the body.

At that time, data was known about the rotation speed and magnetic fields of three celestial bodies- Earth, Sun and White Dwarf - stars E78 from the constellation Virgo.

The magnetic field of a body is characterized by its magnetic moment, the rotation of the body is characterized by its angular momentum (taking into account the size and mass of the body). It has long been known that magnetic moments The Earth and the Sun relate to each other in the same way as their angular moments. Star E78 respected this proportionality! From here it became obvious that there is a direct connection between the rotation of celestial bodies and their magnetic field.

One got the impression that it is the rotation of bodies that causes the magnetic field. Blacket tried to experimentally prove the existence of his proposed law. For the experiment, a gold cylinder weighing 20 kg was made. But the most subtle experiments with the mentioned cylinder yielded nothing. The non-magnetic golden cylinder showed no signs of a magnetic field.

The magnetic and angular momenta of Jupiter have now been established, as well as tentatively that of Venus. Once again, their magnetic fields, divided by angular momenta, are found to be close to the Blackett number. After such a coincidence of coefficients, it is difficult to attribute the matter to chance.

So does the Earth's rotation excite a magnetic field, or does the Earth's magnetic field cause its rotation? For some reason, scientists have always believed that rotation has been inherent in the Earth since its formation. Is this true? Or maybe not! The analogy with our “television” experience raises the question: is it because the Earth rotates around its axis that it, like a large magnet, is in a stream of charged particles? The flow consists mainly of hydrogen nuclei (protons) and helium (alpha particles). Electrons in " solar wind" is not observed, they are probably formed in magnetic traps at the moment of collisions of corpuscles and are born in cascades in zones of the Earth's magnetic field.

EARTH - ELECTROMAGNET

The connection between the magnetic properties of the Earth and its core is now quite obvious. Calculations by scientists show that the Moon does not have a fluid core, therefore it should not have a magnetic field. Indeed, measurements using space rockets have shown that the Moon does not have a noticeable magnetic field around it.

Interesting data were obtained from observations of earth currents in the Arctic and Antarctica. The intensity of earth's electric currents there is very high. It is tens and hundreds of times higher than the intensity in mid-latitudes. This fact indicates that the influx of electrons from the rings of the Earth’s magnetic traps intensively enters the Earth through polar ice caps in the areas of magnetic poles, as in our experience with the TV.

At the moment of intensification solar activity Earth's electric currents also intensify. Now, probably, it can be considered established that electric currents in the Earth are caused by flows of the masses of the Earth’s core and the influx of electrons into the Earth from space, mainly from its radiation rings.

So, electric currents cause the Earth's magnetic field, and the Earth's magnetic field, in turn, apparently causes our Earth to rotate. It is not difficult to guess that the speed of rotation of the Earth will depend on the ratio of negatively and positively charged particles captured by its magnetic field from the outside, as well as those born within the Earth’s magnetic field.

Methodological development of the lesson
Teacher: Item:	Leshchuk L.P. physics
Class:	8
Textbook:	A.V.Grachev, V.A. Pogozhev, E.A. Vishnyakova, M. “Ventana-Graf” 2008
Subject:	Permanent magnets. Earth's magnetic field.
Lesson type:	Lesson of studying and primary consolidation of new knowledge
Goals and objectives
	To create meaningful and organizational conditions for the perception, comprehension and primary memorization of the concepts of “permanent magnet”, “poles of permanent magnets”, “magnetic field”, “magnetic field of the Earth”; with the properties of permanent magnets. Develop skills group work, general educational skills and ICT competencies: working with text, slide presentation. Cultivate a polite attitude towards each other.
Equipment:	Computers, permanent magnets: ceramic circular strip and horseshoe-shaped, metal filings, magnetic needles, pencil, stationery arrows, eraser, plastic pen body, copper wire, sheet of paper, test
Preliminary work:	Preparation of: tests, presentations on the topic, instruction cards.
Organizational chart:	Organizational moment, updating knowledge, learning new material, practicing, monitoring knowledge, lesson results, information about homework.

Organizational stage

Communicating the topic and purpose of the lesson

What's in the black box?

An ancient legend tells about a shepherd named Magnus. He once discovered that the iron tip of his stick and the nails of his boots were attracted to the black stone. This stone began to be called the “Magnus” stone or simply “...”. But another legend is known that the word ... came from the name of the area where they mined iron ore. Many centuries BC. It was known that some rocks have the property of attracting pieces of iron.

(Students' answers)

What do you think will be the subject of study, what will be discussed in class today? (Students answer the question posed). Indeed, we will talk about permanent magnets, as well as the Earth’s magnetic field.

Lesson topic: “Permanent magnets. Earth's magnetic field."

Today we will dive into the world of the science of magnetism, research, interesting facts related to magnetism.

Learning new knowledge and ways of doing things

Student presentation followed by slide show presentation.

Discussion of issues that have arisen.

Are there other ways, besides heating, to demagnetize a magnet?

(If you want to keep the permanent magnet, try not to drop it. This is one way to demagnetize the magnet.)

Does the position of the Earth's magnetic poles remain unchanged?

Practicing the studied material

Students reinforce what they have learned by answering questions by card.

Questions for discussion in groups:

1. What bodies are called permanent magnets?

2. What substances are used to create permanent magnets?

3. What are the poles of a magnet called? What letters represent northern and south pole magnet?

4. Is it possible to make a magnet that has only one pole?

5. How do the poles of magnets interact with each other?

6. What phenomenon is called magnetic induction?

7. How can you get an idea of the magnetic field of a magnet?

8. Where are the North and South magnetic poles of the Earth?

Performing short-term experimental tasks

And now you guys are in progress experimental task Some properties of magnets remain to be investigated. The tasks and instruments are already on your desks. As you complete the tasks, you will draw drawings and draw appropriate conclusions.

Task 1.

Equipment: metal clips, magnets (strip and arc). Take a strip magnet and place a few paper clips exactly in the middle of the magnet, where the border between the red and blue halves is. Does a magnet attract paper clips?

Apply paper clips to different places on the magnet, starting from the middle. Which places show the strongest magnetic effect? Repeat the same with the arc magnet.

Write your conclusions in your notebook.

Conclusions. The line in the middle of the magnet, called the neutral line, exhibits no magnetic properties. The poles of a magnet exhibit the strongest magnetic effect.

Task 2.

Equipment: needle, iron filings, plate of water, cork.

Take a needle and place it on the iron filings. Does sawdust stick to the needle?

Place the needle on the magnet and then place it on the sawdust. Do sawdust stick? Write down your findings in your notebook.

Think about how to make a compass from a needle using a container of water? Did you guess it?

Perform the experiment.

Conclusions. In the first case, the needle did not stick to the sawdust. As soon as the needle “communicated” with the magnet, it itself became a magnet.

There is not much sawdust in the middle of the needle, but the ends are stuck together so that they look like “hedgehogs”.

If you put a magnet needle on a float and let it float in a plate of water, then one end of the needle “looks” to the north and the other to the south. The result is a magnetic compass.

Task 3.

Equipment: magnet and magnetic needle.

1. Apply a magnet to the blue and then to the red end of the magnetic needle. What can be said about the interaction of a magnetic needle and a magnet?

2. Make drawings. Write under them in which case the magnetic needle is attracted and in which it is repelled.

Conclusion. Like poles of a magnet and a magnetic needle repel, opposite poles attract.

(students’ presentations based on the results of the experiment)

Control and mutual verification of knowledge and methods of action
Test on the topic “Permanent magnets. Earth's magnetic field"

1 option

A. magnetically hard.

B. magnetically soft.

B. permanent magnets.

A. Northern. B. Southern.

A. Made of copper. B. Made of steel.

A.magnets. B. ferrites.

A. No. B. Yes. B. Magnets have no poles at all.

Option 2

1. Bodies that maintain a magnetized state for a long time are called...

And permanent magnets.

B. magnetically hard.

B. magnetically soft.

2. A magnet suspended on a thread is installed in the north-south direction. Which pole will the magnet turn to the north pole of the Earth?

A. South. B. Northern.

3. Small iron nails are attracted to the magnet through the rod. What substance is the rod made of: steel or copper?

A. Made of steel. B. Made of copper.

4.Combinations of iron oxides with other elements are called...

A. ferrites. B. magnets.

5. Is it possible to make a strip magnet so that there are poles of the same name at its ends?

A. Yes. B. No. B. Magnets have no poles at all.

Answers to the test