The parallel evolution of the “super-soldier” caste in ants has been explained. Expression of reason: “Thanks to” and “Because of” Due to which the presence was explained

They are porous in body, and therefore the current flows

Can move freely through them without pushing anywhere;

We can classify a tree among this type of thing.

The middle place between both is occupied by iron...

Things in which their fabric coincides with each other.

So, where there is a bulge, the other one would be there

The depression - this connection between them will turn out to be the closest.

There are also those that use hooks and loops as if

They hold tightly and are thus held together by each other.

This most likely occurs in iron with a magnet ... "
About hooks and loops it is said, perhaps, too specifically. However, it is clear to everyone that the ancients perfectly understood the main thing. Besides the magnet, there is something surrounding it. You can talk about the soul, about the atmosphere, about outflows or seeds expelled outward. This is now called a magnetic field. It is this that attracts the iron to the magnet!

The magnificent picture given by Lucretius poetically translates the thesis of Epicurus: “The figures of atoms and indivisible bodies flowing from stone and from iron are so suitable to each other that they easily adhere to each other; so, hitting the hard parts of stone and iron, and then rebounding into the middle, they simultaneously bind to each other and attract the iron.”
The great Plato, an idealist philosopher, commented on the mechanism of magnetic actions: “...due to the fact that there is no emptiness, these bodies push each other on all sides, and when they separate and unite, they all exchange places and move to their usual place . Perhaps those who do proper research will be amazed at these intricate relationships.”

The unique ability of a magnet to attract iron objects was associated in the imagination of the ancients with carnal love, and therefore the first explanations of the attractive effect of these stones were associated with attributing a feminine principle to a magnet and a masculine principle to iron. Sometimes it was the other way around. This, of course, did not change matters at all. The bottom line was that any “attraction”, including the attraction of a magnet, was mechanically equated to one another. The desire of dust particles for amber rubbed on wool, of metal rings for a magnet, of one person for another were considered phenomena of the same order.

The imagination and observation of our ancestors also formed the family of “antimagnets”, i.e. a family of creatures and substances that repel each other. This family also includes people who are antipathetic to each other; and a candle flame repelled by a magnet; and oil that repels water.
In 1269, Pierre Peregrine from Maricourt wrote the book “Letters on the Magnet,” in which he collected a lot of information about the magnet that had accumulated before him and was discovered by him personally. Peregrine speaks for the first time about the poles of magnets, about the attraction (“copulation”) of unlike poles and the repulsion of like ones, about the production of artificial magnets by rubbing iron with a natural magnet, about the penetration of magnetic forces through glass and water, about the compass. The reason for the attraction of the south and north poles was explained rather vaguely by Peregrine and his followers.
Before Gilbert, the phenomenon of “aging of magnets” was also known. Thus, the alchemist Geber (12th century) wrote: “I had a magnet that lifted 100 drachmas of iron. I let it lie there for a while and brought another piece of iron to it. The magnet didn't pick it up. The piece contained 80 drachmas. This means that the strength of the magnet has weakened.”

Other important pre-Gilbertian events include the discovery of magnetic declination in the 14th century, discovered by Columbus in 1492. Changes in the declination of the magnetic needle on the same parallel, as well as the discovery of magnetic inclination by Georg Hartmann (Nuremberg, 1544).

Experience as a criterion of truth

The first scientific attempts to explain magnetic phenomena were made by William Gilbert. In 1600, the book of the English scientist Gilbert “On the Magnet, Magnetic Bodies and the Great Magnet – the Earth” was published. In it, the author described the already known properties of a magnet, as well as his own discoveries.

Gilbert described the phenomenon of magnetic induction, methods of magnetizing iron and steel, etc. Gilbert's book was the first scientific research magnetic phenomena

Gilbert refuted the widely held belief that diamonds influence magnetic properties.

He discovered that when a magnet is heated above a certain temperature, its magnetic properties disappear; subsequently this temperature (588°C) was called the Curie point, in honor of Pierre Curie.
Gilbert discovered that when a piece of iron is brought closer to one pole of a magnet, the other pole begins to attract more strongly. This idea was patented only 250 years after Gilbert's death.
Gilbert discovered that objects made of soft iron, lying motionless for a long time, acquire magnetization in the north-south direction. The magnetization process is accelerated if the iron is tapped with a hammer.

Gilbert discovered the shielding effect of iron. He was the first to say that a magnet with a “helmet” or “nose”, i.e. a magnet set in soft iron fittings attracts much more strongly. Gilbert expressed the brilliant idea that the action of a magnet spreads like light.

Gilbert's book was the first scientific study of magnetic phenomena

Gilbert did and discovered a lot. But... Gilbert could hardly explain anything. All his reasoning is scholastic and naive.

Eureka

On February 15, 1820, Oersted, already an emeritus professor, lectured students on physics. On the laboratory table there was a voltaic pole, a wire connecting it, clamps and a compass. While Oersted closed the circuit, the compass needle trembled and turned towards the wire. This was the first direct confirmation of the connection between electricity and magnetism. This was what all European and American physicists had been looking for for so long.

It should be said that the deviation of the compass needle in the lecture experiment was very insignificant, and therefore in July 1820 Oersted repeated the experiment again, using more powerful batteries. The effect was much stronger, and the stronger the thicker the wire with which he closed the battery contacts. (The larger the diameter of the wire, the lower its resistance and, therefore, the greater the short-circuit current.) In addition, he found out one strange thing that does not fit into Newton’s ideas about action and reaction. In his own words, “the magnetic effect of electric current has a circular motion.”

Appendix No. 2

"Loving Stone"

The Chinese say that a loving stone, Tshu-shi, attracts iron, like a tender mother attracts her children. It is remarkable that among the French, a people living at the opposite end of the Old World, we find a similar name for a magnet - the French word aimant means both magnet and lover. The strength of this love in natural magnets is insignificant, and therefore the Greek name for the magnet, Hercules stone, sounds very naive. If the inhabitants of ancient Hellas were so amazed by the moderate attractive force of a natural magnet, then what would they say if they saw magnets in a modern metallurgical plant that lift blocks weighing whole tons? True, these are not natural magnets, but electromagnets, i.e. iron masses magnetized by an electric current passing through a winding surrounding them. But in both cases the force of the same nature acts: magnetism. Substances that attract iron were known to mankind more than 2000 years ago. They are called magnets. A permanent magnet in the form of a thin strip, located on a wooden plank floating in water, turns with one end in the direction of the North Pole of the Earth, and the other in the direction of the South Pole. That's why the ends of a magnet are called the north and south poles.
This observation led to the creation of the compass. The first compasses appeared in China. In Europe, the compass began to be used in the 12th century. In 1600 The English physicist W. Gilbert published a large work on the magnet, in which he described many experiments carried out over 18 years. He was the first to come to the conclusion that the Earth itself is a large magnet. “Loving stone” is the poetic name the Chinese gave to a natural magnet. A loving stone (tshu-shi), as the Chinese say, attracts iron, just as a tender mother attracts her children. It is remarkable that among the French, a people living at the opposite end of the Old World, we find a similar name for a magnet: the French word “aimant” means both “magnet” and “loving”.
The strength of this “love” in natural magnets is insignificant, and therefore the Greek name for the magnet, “Hercules Stone,” sounds very naive. If the inhabitants of ancient Hellas were so amazed by the moderate force of attraction of a natural magnet, then what would they say if they saw magnets in a modern metallurgical plant that lift blocks weighing whole tons! True, these are not natural magnets, but “electromagnets,” i.e., iron masses magnetized by an electric current passing through the winding surrounding them. But in both cases the force of the same nature acts - magnetism.
You should not think that a magnet only acts on iron. There are a number of other bodies that also experience the action of a strong magnet, although not to the same extent as iron. Metals: nickel, cobalt, manganese, platinum, gold, silver, aluminum are weakly attracted by a magnet. Even more remarkable are the properties of the so-called diamagnetic bodies, for example zinc, lead, sulfur, bismuth: these bodies are repelled by a strong magnet!
Liquids and gases also experience the attraction or repulsion of a magnet, although to a very weak extent; the magnet must be very strong to exert its influence on these substances. Pure oxygen, for example, is attracted by a magnet; If you fill a soap bubble with oxygen and place it between the poles of a strong electromagnet, the bubble will noticeably stretch from one pole to the other, stretched by invisible magnetic forces. The candle flame between the ends of a strong magnet changes its usual shape, clearly showing sensitivity to magnetic forces (Fig. 90).

Figure 90. Candle flame between the poles of an electromagnet.

Appendix No. 3

"Documentary" evidence"

The oldest “documentary” evidence of people’s acquaintance with magnets came to us from Central America. In the town square of the Guatemalan town of Demokrasia stands a dozen ancient figures found during excavations of an Olmec site. “Fat boys,” as they were called for their roundness and massiveness, are symbols of satiety, well-being, and fertility. These sculptures were carved from blocks of magnetic rock more than three thousand years ago. It’s interesting that magnetic lines of force seem to come out of the belly of “fat people”! By the way, in addition to the “fat boys”, the ancient Olmecs knew how to carve figures sea ​​turtles with a magnetized head, possibly linking the ability of turtles to find a course in the open sea with the properties of a magnet to navigate in the Earth's magnetic field.
In Chinese chronicles there are descriptions of magnetic gates through which an ill-wisher with a weapon could not pass, as well as magnetic pavements and other uses of the magic stone chu-shi, simply magnetic iron ore. Another legend tells of the military victory of Emperor Huang-Ti, won more than three thousand years ago. He owed this victory to his craftsmen, who made the carts on which were mounted figures of a man with an arm extended forward. The figures could rotate, but the outstretched arm always pointed south. With the help of such carts, Huang-Ti was able to attack the enemy from the rear in thick fog and defeat him.

The ancient Greeks knew that there was a special mineral - iron ore(magnetic iron ore), capable of attracting iron objects. Deposits of this mineral were located near the city of Magnesia. The name of this city served as the source of the term "magnet".

The ancients did not study either electrical or magnetic phenomena. However, they tried to explain these phenomena.

The very first explanation for the properties of a magnet to attract iron was that a “soul” was attributed to the magnet, which caused the magnet to attract iron or be attracted to iron.

At the same time, the magnet was represented as a living creature. A living creature, such as a dog, sees a piece of meat and strives to approach it. Similarly, a magnet seems to see iron and strives to be attracted to it.

This explanation is very primitive from our point of view. However, this kind of explanation, when objects inanimate nature animated, were characteristic of the ancients, who believed in the existence of a number of gods, spirits, etc.

But in ancient times, materialist philosophy also began to develop. Materialist philosophers Ancient Greece rejected the existence of spirits and tried to explain all natural phenomena by natural laws.

They taught that all bodies consist of small material indivisible particles - atoms. In their opinion, nothing exists except atoms and the void in which atoms move. All natural phenomena are explained by the movement of atoms. The very word "atom" Greek origin. It means "indivisible."

Philosophers who believed in the existence of atoms that make up nature were called atomists. One of the founders of this philosophy was the ancient Greek philosopher Democritus (460 - 370 BC). Atomistic philosophers tried to explain electrical and magnetic phenomena without resorting to special “souls” and “spirits.”

In the Middle Ages, the study of magnetic phenomena acquired practical importance. This occurs in connection with the invention of the compass.

Already in the 12th century. In Europe, the compass became known as a device with which you can determine the direction of parts of the world. Europeans learned about the compass from the Arabs, who by this time already knew the property of a magnetic needle. Even earlier, this property was probably known in China (Based on the information given in the oldest Chinese encyclopedias, we can guess that between 300 and 400 BC, the magnetic needle was used on ships. If we move on from the legends to firmly established facts, the compass will become significantly “younger.” Thus, the museum houses a Chinese compass “only” a thousand years ago, reminiscent in shape of our Khokhloma spoon.)

Since the 12th century. The compass was increasingly used in sea ​​travel to determine the course of a ship on the open sea.

The practical application of magnetic phenomena led to the need to study them. A number of properties of magnets were gradually revealed.

In 1600, the book of the English scientist Gilbert “On the Magnet, Magnetic Bodies and the Great Magnet – the Earth” was published. In it, the author described the already known properties of a magnet, as well as his own discoveries.

Even earlier we learned that a magnet always has two poles. They were named after parts of the world - the north pole and the south pole. Among the properties of a magnet, Gilbert pointed out that like poles repel, and unlike poles attract.

Gilbert assumed that the Earth was a large magnet. To confirm this assumption, Hilbert performed a special experiment. He carved a large ball from a natural magnet. By bringing a magnetic needle closer to the surface of the ball, he showed that it is always installed in a certain position, just like the compass needle on the earth.

Gilbert described the phenomenon of magnetic induction, methods of magnetizing iron and steel, etc. Gilbert's book was the first scientific study of magnetic phenomena.

Lightning gave the right direction to scientists' thoughts about the nature of magnetism, as in the case of electricity.

At the beginning of the 19th century, the French scientist Francois Arago published the book “Thunder and Lightning.” This book contains several interesting entries, some of which may have led to Arago's friend, the French physicist André-Marie Ampère, giving the first correct explanation of magnetism. Mathematics, mechanics and physics owe important research to Ampere. His main physical work was carried out in the field of electrodynamics. In 1820 he established a rule for determining the direction of action magnetic field on the magnetic needle, now known as Ampere's rule; conducted many experiments to study the interaction between a magnet and electric current; for these purposes he created a number of devices; discovered that the Earth's magnetic field affects moving current-carrying conductors. In the same year, he discovered the interaction between electric currents, formulated the law of this phenomenon (Ampere's law), developed the theory of magnetism, and proposed the use of electromagnetic processes for transmitting signals.

Appendix No. 4

"Achievements.A. M. Ampere in the study of magnetic phenomena"

French physicist Andre-Marie Ampère was the first to give a correct explanation of magnetism. Mathematics, mechanics and physics owe important research to Ampere. His main physical work was carried out in the field of electrodynamics. In 1820, he established a rule for determining the direction of action of a magnetic field on a magnetic needle, now known as Ampere's rule; conducted many experiments to study the interaction between a magnet and electric current; for these purposes he created a number of devices; discovered that the Earth's magnetic field affects moving current-carrying conductors. In the same year, he discovered the interaction between electric currents, formulated the law of this phenomenon (Ampere's law), developed the theory of magnetism, and proposed the use of electromagnetic processes for transmitting signals.
According to Ampere's theory, magnetic interactions are the result of the interactions of so-called circular molecular currents occurring in bodies, equivalent to small flat magnets, or magnetic sheets. This statement is called Ampere's theorem. Thus, a large magnet, according to Ampere’s ideas, consists of many such elementary magnets. This is the essence of the scientist’s deep conviction in the purely current origin of magnetism and its close connection with electrical processes.

In 1822, Ampere discovered the magnetic effect of a solenoid (coil with current), which led to the idea that a solenoid is equivalent to a permanent magnet. They were also asked to enhance the magnetic field using an iron core placed inside the solenoid. Ampere’s ideas were presented by him in the works “Code of Electrodynamic Observations” (French: “Recueil d’observations electrodynamiques”, Paris, 1822), “ Short course theory of electrodynamic phenomena" (French "Precis de la théorie des phenomenes electrodynamiques", Paris, 1824), "Theory of electrodynamic phenomena" (French "Theorie des phenomenes electrodynamiques"). In 1826, he proved a theorem about the circulation of the magnetic field. In 1829, Ampère invented devices such as the commutator and the electromagnetic telegraph.
Ampere. A modest, almost invisible titanium during life. And a very unhappy person.

He was ugly, awkward, and therefore, probably, incredibly shy. His friends said that at times they thought he was embarrassed by his own shadow. He never took care of himself. He dressed almost casually, even sloppily, and this did not bother him at all. He humbly endured all the blows of fate, although not resignedly - he often complained how unfair this fate was to him, he could even cry, not hiding his tears from the ladies. And in general, he always seemed to obediently float with the flow of life.
And suddenly a powerful pressure of the mind, purposeful concentration, an unstoppable onslaught in work, a brave throw into the unknown...
It's amazing how it all came together...

Appendix No. 5

"G. Chr. Ersted, professor of physics in Copenhagen"

The first experiments concerning what I intend to find out were made during the lectures on electricity, galvanism and magnetism that I gave last winter. From these experiments it was apparently clear that under the action of a galvanic device the magnetic needle is moved out of its position and, moreover, with a closed galvanic circuit, and not with an open one (some famous physicists tried in vain to do the latter several years ago). But since these experiments were carried out with a not very strong instrument and, as a result, the resulting phenomena were insufficient for such an important question, I took my friend, the justice of the city, as my assistant.Esmarch, to once again carry out the experiments using a large galvanic device that we built together. The head of the local administration of the city was also present during our experiments.Vleigelas a participant and witness. Moreover, they were witnessed by the long-known excellent physicist, Obergoffmarshal Mr.Gauch, professor of natural historyReinhard, professor of medicineJacobson, an excellent experimenter and expert in chemistry, Ph.D.Zeise. Very often I experimented alone, but whenever I noticed new phenomena, I reproduced them again in the presence of these scientists.

Appendix No. 6

“Test to check the mastery of educational elements”

Answers at the very bottom of the embedded document

A magnetic field
Test 1
Option 1
A1. Thanks to this, the presence of magnesium in substances was explained.
thread properties?
1) thanks to Oersted's hypothesis;
2) thanks to Newton's first law;
3) thanks to Einstein's theory;
4) thanks to Ampere's hypothesis.
A2. Finish the sentence.
“One of the properties of a magnetic field is the ability to exert an effect
vien a...”
1) stationary charges;
2) moving charges;
3) stationary and moving charges;
4) all particles.
AZ. What is the magnitude of the magnetic induction vector?
1) /S7; 3) IS cos a;
2) _^£max_ 4)0.
IS
A4. What formula should be used to determine the ampere force modulus?
1) IBlsin a, where a = (B; /); 3) IBCosa;
2) IBS cosa; 4) there is no such formula.
A5. How to find the Lorentz force?
1) there is no such formula; 3) Fn = qvBs in a ;
2) Fn = qvBcosa ; 4) Fn = qvBSsina ;
A6. The figure shows a coil of wire through which flows
electric current in the direction indicated by the arrow. The coil is located
laid in a horizontal plane. Where is the inductance vector directed?
tion of the magnetic field of the current in the center of the coil?
1) vertically up T;
2) horizontally to the left;
3) horizontally to the right ->;
4) vertically down 4-.
A7. How do two conductors parallel to each other interact?
ka, if the electric current flows in them in opposite directions
boards?
A magnetic field. Test 1 5
With
1) the interaction force is zero;
2) conductors attract;
3) conductors repel;
4) the conductors turn in the same direction.
A8. A coil of wire is in a magnetic field, perpendicular to
nom to the plane of the coil, and its ends are closed to an ammeter.
Magnetic induction of the field me-
changes over time
according to the traffic in the picture.
In what period of time
The ammeter will show the presence
electric current in a turn?
1) from 0 to 1 s;
2) from 1 to 3 s;
3) from 3 to 4 s;
4) at all time intervals
Menu from 0 to 4 s.
A9. In a uniform magnetic field there is
there is a frame through which current begins to flow
(see picture). Where the force is directed, the effect
blowing onto the top side of the frame?
1) down;
2) up;
3) from the plane of the sheet towards us;
4) in the plane of the sheet from us.
IN
J
1
\
----1 “I g -
A10. Three electrons are placed in a uniform magnetic field,
the motion boards of which are shown
on the image. On which of the electrons is not
the force exerted by the magnetic
fields?
1) U
2) 2;
3) 3;
4) 1 and 2.
All. A charged particle moves in a circle in a uniform
magnetic field. How does the frequency of revolution of a particle change when
reducing its kinetic energy by 2 times?
1) will decrease by 2 times;
2) will decrease by \)