Experts note that Earth's magnetic poles are shifting with a high increasing speed, and magnetic field weakens. What dangers does this pose, how can this phenomenon threaten humanity, and perhaps all nature and fauna?
Let's try to briefly understand this issue, calling on domestic and foreign sources for help. After all, the compass needle points to the north - this is what children are taught in geography lessons.
Was there a pole shift earlier in Earth's history?
Yes, it was, scientists say. 786,000 years ago, the Earth's magnetic field changed its direction by 180 degrees. The reversal apparently lasted only a hundred years, but looking ahead, we can assume that people could still be in some danger then.
Moreover, the Earth's magnetic field has changed direction several times - on average every 250,000 years. At that time, if there was a compass, then its arrow, indicating north, would actually show south.
The last long-term reversal of the magnetic poles, called the Brunhes-Matuyama reversal, occurred almost 800 thousand years ago. And it happened surprisingly much faster than previously known polarity reversals magnetic field Earth, as reported in the International Geophysical Journal.
Almost as quickly was a brief change in the magnetic field 41,000 years ago. At that time, the magnetic north pole traveled 200 years to the south pole, stayed there for 440 years, and then returned north. Such short-term excursions are made even more often than long-term reversals.
The exact date of the last long-term magnetic pole reversal
To analyze the shifting magnetic poles, scientists analyzed sediments from a former lake in the Apennines east of Rome. The dominant directions of the magnetic field of their sediment materials were found and restored. In this study, scientists were able to determine the timing of the Brunhes-Matuyama turn much more accurately than was previously possible. The ratio of two different argon isotopes was used to calculate the age of the deposited layers. It turned out that this event happened only 786 thousand years ago.
Researchers still cannot fully explain why the Earth’s magnetic field changes its direction. "This is due to changes in the planet's outer core," says Maxwell Braun of the German Research Center for Geosciences in Potsdam. This is where the Earth's magnetic field is probably generated. "However, we don't know what controls its long-term behavior."
However, there is also an understanding of the nature of the Earth's magnetic field. The reasons for the formation of the magnetic field are hidden deep in the hot bowels of the Earth: there is a layer of liquid iron that rotates around the 2500-kilometer powerful core of the Earth, which consists of solid metal - iron and nickel. This rotation moves metals over distances of approximately ten kilometers per year and creates a current, which in turn generates a magnetic field around the Earth.
“But the iron masses in the bowels of the earth behave chaotically, slight turbulence and convection currents form everywhere, which manifests itself on the earth in the form of oscillations in the magnetic field, both further weakening the magnetic field and slightly strengthening it in other places. Thus, the magnetic field has already weakened by 5%, and even more in the Atlantic and Brazil.
There is at least indirect evidence that the next pole switch could take place within a few thousand years. The Earth's magnetic field has been weakening for 150 years. Recently, the decrease in field intensity has even accelerated. And the North Magnetic Pole, for example, has already traveled from its original value of 1300 km in the direction of Siberia, covering approximately 90 km per day.
What dangers and threats does the switching of the Earth’s magnetic field pose for all living things?
For life on Earth, orbiting satellites and electrical infrastructure, the Earth's magnetic field is extremely important because it protects them from harmful cosmic radiation. During the reversal, the magnetic field becomes much weaker. Protection from cosmic radiation is reduced and this may increase the risk of cancer for humans and animals. The impact on satellites will occur in much the same way as during solar storms. Experts fear disruptions in the functioning of the power grid.
Moreover, the magnetic field prevents molecules of the Earth’s gaseous shell from being carried away into space, otherwise what would be left of it would be what is now observed on Mars.
However, geologists are calm about the polarity reversal because the atmosphere is a real shield against high energy radiation towards the earth. In addition, the protective magnetic field does not disappear completely even during a reversal. It is somewhat encouraging that the human race has experienced several short-term magnetic field reversals, such as the one that took place 41,000 years ago.
Currently, scientists have begun intensive research polar ice, which keeps the age-old secrets of the response of materials to changes in the planet’s magnetic field. Many believe that in this matter, earthlings simply have a glaring lack of knowledge, which must be quickly eliminated. Maybe that’s why, for more than one year now, three European satellites have begun to fly close to each other in Earth’s orbit, and with their magnetometers they carefully monitor changes in the magnetic field of our planet. And they noted a decrease in the field weakening intensity in a number of places. True, in other places these changes have increased somewhat.
But astrophysicist Harald Lescha from Munich, who carried out computer simulations of the problem, gives unexpected hope to humanity. He says that if the planet’s magnetic field weakens greatly, then the missing energy can be replaced by the energy of people directed towards the magnetic field.
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L. Tarasov
Fragment from the book: Tarasov L.V. Terrestrial magnetism. - Dolgoprudny: Publishing House "Intelligence", 2012.
Science and life // Illustrations
The edge of the ice shelf now named Ross.
Route of the Amundsen expedition of 1903-1906.
The drift path of the South Magnetic Pole based on the results of expeditions of different years.
Daily path according to the results of the 1994 expedition, which passes the South Magnetic Pole on a calm day (inner oval) and on a magnetically active day (outer oval). The middle point is located in the western part of the island of Ellef-Ringnes and has coordinates 78°18’N. w. and 104°00’W. d. It has shifted relative to James Ross’s starting point by almost 1000 km!
The path of magnetic pole drift in Antarctica from 1841 to 2000. Shown are the positions of the North Magnetic Pole established during expeditions in 1841 (James Ross), 1909, 1912, 1952, 2000. Black squares mark some stationary stations in Antarctica.
“Our universal mother Earth is a big magnet!” - said the English physicist and doctor William Gilbert, who lived in the 16th century. More than four hundred years ago, he made the correct conclusion that the Earth is a spherical magnet and its magnetic poles are the points where the magnetic needle is oriented vertically. But Gilbert was wrong in believing that the Earth's magnetic poles coincide with its geographic poles. They don't match. Moreover, if the positions of the geographic poles are unchanged, then the positions of the magnetic poles change over time.
1831: First determination of the coordinates of the magnetic pole in the Northern Hemisphere
In the first half of the 19th century, the first searches for magnetic poles were undertaken based on direct measurements of magnetic inclination on the ground. (Magnetic inclination is the angle by which the compass needle deviates under the influence of the Earth’s magnetic field in the vertical plane. - Ed.)
The English navigator John Ross (1777-1856) sailed in May 1829 on the small steamer Victoria from the coast of England, heading to the Arctic coast of Canada. Like many daredevils before him, Ross hoped to find a northwest sea route from Europe to East Asia. But in October 1830, ice trapped the Victoria at the eastern tip of the peninsula, which Ross named Boothia Land (in honor of the expedition's sponsor, Felix Booth).
Trapped in the ice off the coast of Butia Earth, the Victoria was forced to stay here for the winter. The captain's mate on this expedition was John Ross's young nephew, James Clark Ross (1800-1862). At that time, it had already become common practice to take with you on such trips all the necessary instruments for magnetic observations, and James took advantage of this. During the long winter months, he walked along the coast of Butia with a magnetometer and made magnetic observations.
He understood that the magnetic pole must be somewhere nearby - after all, the magnetic needle invariably showed very large inclinations. By plotting the measured values on a map, James Clark Ross soon realized where to look for this unique point with the vertical direction of the magnetic field. In the spring of 1831, he, along with several members of the Victoria crew, sailed 200 km towards the west coast of Boothia and on June 1, 1831 at Cape Adelaide with coordinates 70°05’ N. w. and 96°47’W. d. found that the magnetic inclination was 89°59'. This is how the coordinates of the magnetic pole in the Northern Hemisphere were determined for the first time - in other words, the coordinates of the South Magnetic Pole.
1841: First determination of the coordinates of the magnetic pole in the Southern Hemisphere
In 1840, the grown-up James Clark Ross set out on the ships Erebus and Terror on his famous voyage to the magnetic pole in the Southern Hemisphere. On December 27, Ross's ships first encountered icebergs and already on New Year's Eve 1841 crossed the Antarctic Circle. Very soon, Erebus and Terror found themselves in front of the pack ice that stretched from edge to edge of the horizon. On January 5, Ross made the bold decision to go forward, straight onto the ice, and go as deep as possible. And after just a few hours of such an assault, the ships unexpectedly emerged into a more ice-free space: the pack ice was replaced by individual ice floes scattered here and there.
On the morning of January 9, Ross unexpectedly discovered an ice-free sea ahead of him! This was his first discovery on this journey: he discovered the sea, which was later called his own name, - Ross Sea. To the right of the course there was mountainous, snow-covered land, which forced Ross's ships to sail south and which, it seemed, was not going to end. Sailing along the coast, Ross, of course, did not miss the opportunity to discover the southernmost lands for the glory of the British kingdom; This is how Queen Victoria Land was discovered. At the same time, he was worried that on the way to the magnetic pole the coast could become an insurmountable obstacle.
Meanwhile, the behavior of the compass became more and more strange. Ross, who had extensive experience in magnetometric measurements, understood that no more than 800 km remained to the magnetic pole. No one had ever come so close to him before. It soon became clear that Ross’s fears were not in vain: the magnetic pole was clearly somewhere to the right, and the coast stubbornly directed the ships further and further south.
As long as the path was open, Ross did not give up. It was important for him to collect at least as much magnetometric data as possible at different points on the coast of Victoria Land. On January 28, the expedition received the most amazing surprise of the entire trip: a huge awakened volcano grew on the horizon. Above him hung a dark cloud of smoke, colored by fire, which erupted from the vent in a column. Ross gave the name Erebus to this volcano, and gave the name Terror to the neighboring one, which was extinct and somewhat smaller.
Ross tried to go even further south, but very soon a completely unimaginable picture appeared before his eyes: along the entire horizon, as far as the eye could see, stretched a white stripe, which became higher and higher as it approached! As the ships came closer, it became clear that in front of them to the right and left was a huge endless ice wall 50 meters high, completely flat on top, without any cracks on the side facing the sea. This was the edge of the ice shelf that now bears the name Ross.
In mid-February 1841, after a 300-kilometer voyage along the ice wall, Ross decided to stop further attempts to find a loophole. From that moment on, there was only the road home ahead.
Ross's expedition cannot be considered a failure. After all, he was able to measure the magnetic inclination at many points around the coast of Victoria Land and thereby establish the position of the magnetic pole with high accuracy. Ross indicated the following coordinates of the magnetic pole: 75°05’ S. latitude, 154°08’ e. d. The minimum distance separating the ships of his expedition from this point was only 250 km. It is Ross's measurements that should be considered the first reliable determination of the coordinates of the magnetic pole in Antarctica (North Magnetic Pole).
Coordinates of the magnetic pole in the Northern Hemisphere in 1904
73 years have passed since James Ross determined the coordinates of the magnetic pole in the Northern Hemisphere, and now the famous Norwegian polar explorer Roald Amundsen (1872-1928) has undertaken a search for the magnetic pole in this hemisphere. However, the search for the magnetic pole was not the only goal of Amundsen's expedition. The main goal was to open the northwestern sea route from Atlantic Ocean in Quiet. And he achieved this goal - in 1903-1906 he sailed from Oslo, past the shores of Greenland and Northern Canada to Alaska on the small fishing vessel Gjoa.
Amundsen subsequently wrote: “I wanted my childhood dream of a northwest sea route to be combined in this expedition with another, much more important scientific goal: finding the current location of the magnetic pole.”
He approached this scientific task with all seriousness and carefully prepared for its implementation: he studied the theory of geomagnetism from leading specialists in Germany; I also purchased magnetometric instruments there. Practicing working with them, Amundsen traveled all over Norway in the summer of 1902.
By the beginning of the first winter of his journey, in 1903, Amundsen reached King William Island, which was very close to the magnetic pole. The magnetic inclination here was 89°24'.
Deciding to spend the winter on the island, Amundsen simultaneously created a real geomagnetic observatory here, which carried out continuous observations for many months.
The spring of 1904 was devoted to observations “in the field” in order to determine the coordinates of the pole as accurately as possible. Amundsen was successful and discovered that the position of the magnetic pole had shifted noticeably to the north relative to the point at which the expedition of James Ross found it. It turned out that from 1831 to 1904 the magnetic pole moved 46 km to the north.
Looking ahead, we note that there is evidence that during this 73-year period the magnetic pole did not just move slightly to the north, but rather described a small loop. Around 1850, it first stopped moving from northwest to southeast and only then began a new journey to the north, which continues today.
Drift of the magnetic pole in the Northern Hemisphere from 1831 to 1994
The next time the location of the magnetic pole in the Northern Hemisphere was determined was in 1948. A months-long expedition to the Canadian fjords was not needed: after all, the place could now be reached in just a few hours - by air. This time, the magnetic pole in the Northern Hemisphere was discovered on the shores of Lake Allen on Prince of Wales Island. The maximum inclination here was 89°56’. It turned out that since the time of Amundsen, that is, since 1904, the pole has “moved” to the north by as much as 400 km.
Since then, the exact location of the magnetic pole in the Northern Hemisphere (South Magnetic Pole) has been determined regularly by Canadian magnetologists at intervals of about 10 years. Subsequent expeditions took place in 1962, 1973, 1984, 1994.
Not far from the location of the magnetic pole in 1962, on Cornwallis Island, in the town of Resolute Bay (74°42'N, 94°54'W), a geomagnetic observatory was built. Nowadays, traveling to the South Magnetic Pole is just a fairly short helicopter ride from Resolute Bay. It is not surprising that with the development of communications in the 20th century, tourists began to visit this remote town in northern Canada more and more often.
Let us pay attention to the fact that when speaking about the magnetic poles of the Earth, we are actually talking about certain averaged points. Since the time of Amundsen's expedition, it has become clear that even over the course of one day, the magnetic pole does not stand still, but makes small “walks” around a certain midpoint.
The reason for such movements, of course, is the Sun. Streams of charged particles from our star (solar wind) enter the Earth's magnetosphere and generate in the earth's ionosphere electric currents. These, in turn, generate secondary magnetic fields that disturb the geomagnetic field. As a result of these disturbances, the magnetic poles are forced to take their daily walks. Their amplitude and speed naturally depend on the strength of the disturbances.
The route of such walks is close to an ellipse, with the pole in the Northern Hemisphere traversing clockwise, and in the Southern Hemisphere counterclockwise. The latter, even on days of magnetic storms, moves no more than 30 km from the midpoint. The pole in the Northern Hemisphere on such days can move away from the midpoint by 60-70 km. On calm days, the sizes of daily ellipses for both poles are significantly reduced.
Magnetic pole drift in the Southern Hemisphere from 1841 to 2000
It should be noted that historically, the situation with measuring the coordinates of the magnetic pole in the Southern Hemisphere (North Magnetic Pole) has always been quite difficult. Its inaccessibility is largely to blame. If you can get from Resolute Bay to the magnetic pole in the Northern Hemisphere by small airplane or helicopter in a few hours, then from the southern tip of New Zealand to the coast of Antarctica you need to fly more than 2000 km over the ocean. And after that it is necessary to conduct research in the difficult conditions of the ice continent. To properly appreciate the inaccessibility of the North Magnetic Pole, let’s go back to the very beginning of the 20th century.
For quite a long time after James Ross, no one dared to go deep into Victoria Land in search of the North Magnetic Pole. The first to do this were members of the expedition of the English polar explorer Ernest Henry Shackleton (1874-1922) during his voyage in 1907-1909 on the old whaling ship Nimrod.
On January 16, 1908, the ship entered the Ross Sea. Too thick pack ice off the coast of Victoria Land for a long time made it impossible to find an approach to the shore. Only on February 12 was it possible to transfer the necessary things and magnetometric equipment to the shore, after which the Nimrod headed back to New Zealand.
It took the polar explorers who remained on the shore several weeks to build more or less acceptable housing. Fifteen brave souls learned to eat, sleep, communicate, work and generally live in incredibly difficult conditions. There was a long polar winter ahead. Throughout the winter (in the Southern Hemisphere it comes at the same time as our summer), members of the expedition were engaged in scientific research: meteorology, geology, measuring atmospheric electricity, studying the sea through cracks in the ice and the ice itself. Of course, by spring the people were already quite exhausted, although the main goals of the expedition were still ahead.
On October 29, 1908, one group, led by Shackleton himself, set out on a planned expedition to the Geographic South Pole. True, the expedition was never able to reach it. On January 9, 1909, just 180 km from the South Geographic Pole, in order to save hungry and exhausted people, Shackleton decides to leave the expedition flag here and turn the group back.
The second group of polar explorers, led by the Australian geologist Edgeworth David (1858-1934), independently of Shackleton's group, set off on a journey to the magnetic pole. There were three of them: David, Mawson and Mackay. Unlike the first group, they had no experience in polar exploration. Having left on September 25, they were already behind schedule by the beginning of November and, due to overconsumption of food, were forced to go on strict rations. Antarctica taught them harsh lessons. Hungry and exhausted, they fell into almost every crevice in the ice.
On December 11, Mawson almost died. He fell into one of the countless crevasses, and only a reliable rope saved the researcher’s life. A few days later, a 300-kilogram sled fell into a crevasse, almost dragging down three people, exhausted from hunger. By December 24, the health of the polar explorers had seriously deteriorated; they suffered simultaneously from frostbite and sunburn; McKay also developed snow blindness.
But on January 15, 1909, they still achieved their goal. Mawson's compass showed a deviation of the magnetic field from the vertical of only 15'. Leaving almost all their luggage in place, they reached the magnetic pole in one throw of 40 km. The magnetic pole in the Southern Hemisphere of the Earth (North Magnetic Pole) has been conquered. After hoisting the British flag at the pole and taking photographs, the travelers shouted “Hurrah!” three times. King Edward VII and declared this land the property of the British crown.
Now they had only one thing to do - stay alive. According to the calculations of the polar explorers, in order to keep up with the departure of Nimrod on February 1, they had to travel 17 miles a day. But they were still four days late. Fortunately, Nimrod himself was delayed. So soon the three intrepid explorers were enjoying a hot dinner on board the ship.
So, David, Mawson and Mackay were the first people to set foot on the magnetic pole in the Southern Hemisphere, which on that day was located at coordinates 72°25' S. latitude, 155°16’ e. (300 km from the point measured at one time by Ross).
It is clear that there was no talk of any serious measuring work here. The vertical inclination of the field was recorded only once, and this served as a signal not for further measurements, but only for a speedy return to the shore, where the warm cabins of the Nimrod awaited the expedition. Such work to determine the coordinates of the magnetic pole cannot even be closely compared with the work of geophysicists in Arctic Canada, who spend several days conducting magnetic surveys from several points surrounding the pole.
However, the last expedition (the 2000 expedition) was carried out quite high level. Since the North Magnetic Pole had long since left the continent and was in the ocean, this expedition was carried out on a specially equipped vessel.
Measurements showed that in December 2000, the North Magnetic Pole was opposite the coast of Terre Adelie at a point with coordinates 64°40’ S. w. and 138°07’E. d.
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According to modern ideas, it was formed approximately 4.5 billion years ago, and from that moment our planet has been surrounded by a magnetic field. Everything on Earth, including people, animals and plants, is affected by it.
The magnetic field extends to an altitude of about 100,000 km (Fig. 1). It deflects or captures solar wind particles that are harmful to all living organisms. These charged particles form the Earth's radiation belt, and the entire region of near-Earth space in which they are located is called magnetosphere(Fig. 2). On the side of the Earth illuminated by the Sun, the magnetosphere is limited by a spherical surface with a radius of approximately 10-15 Earth radii, and on the opposite side it is extended like a comet's tail over a distance of up to several thousand Earth radii, forming a geomagnetic tail. The magnetosphere is separated from the interplanetary field by a transition region.
Earth's magnetic poles
The axis of the earth's magnet is inclined relative to the earth's rotation axis by 12°. It is located approximately 400 km away from the center of the Earth. The points at which this axis intersects the surface of the planet are magnetic poles. The Earth's magnetic poles do not coincide with the true geographic poles. Currently, the coordinates of the magnetic poles are as follows: north - 77° north latitude. and 102°W; southern - (65° S and 139° E).
Rice. 1. The structure of the Earth’s magnetic field
Rice. 2. Structure of the magnetosphere
Lines of force running from one magnetic pole to another are called magnetic meridians. An angle is formed between the magnetic and geographic meridians, called magnetic declination. Every place on Earth has its own declination angle. In the Moscow region the declination angle is 7° to the east, and in Yakutsk it is about 17° to the west. This means that the northern end of the compass needle in Moscow deviates by T to the right of the geographic meridian passing through Moscow, and in Yakutsk - by 17° to the left of the corresponding meridian.
A freely suspended magnetic needle is located horizontally only on the line of the magnetic equator, which does not coincide with the geographical one. If you move north of the magnetic equator, the northern end of the needle will gradually descend. The angle formed by a magnetic needle and a horizontal plane is called magnetic inclination. At the North and South magnetic poles, the magnetic inclination is greatest. It is equal to 90°. At the North Magnetic Pole, a freely suspended magnetic needle will be installed vertically with its northern end down, and at the South Magnetic Pole its southern end will go down. Thus, the magnetic needle shows the direction of the magnetic field lines above the earth's surface.
Over time, the position of the magnetic poles relative to the earth's surface changes.
The magnetic pole was discovered by explorer James C. Ross in 1831, hundreds of kilometers from its current location. On average, it moves 15 km in one year. IN last years the speed of movement of the magnetic poles increased sharply. For example, the North Magnetic Pole is currently moving at a speed of about 40 km per year.
The reversal of the Earth's magnetic poles is called magnetic field inversion.
Throughout the geological history of our planet, the Earth's magnetic field has changed its polarity more than 100 times.
The magnetic field is characterized by intensity. In some places the Earth is magnetic power lines deviate from the normal field, forming anomalies. For example, in the area of the Kursk Magnetic Anomaly (KMA), the field strength is four times higher than normal.
There are daily variations in the Earth's magnetic field. The reason for these changes in the Earth's magnetic field is the electric currents flowing in the atmosphere at high altitude. They are caused by solar radiation. Under the influence of the solar wind, the Earth's magnetic field is distorted and acquires a “trail” in the direction from the Sun, which extends for hundreds of thousands of kilometers. The main cause of the solar wind, as we already know, is the enormous ejections of matter from the solar corona. As they move towards the Earth, they turn into magnetic clouds and lead to strong, sometimes extreme disturbances on the Earth. Particularly strong disturbances of the Earth's magnetic field - magnetic storms. Some magnetic storms begin suddenly and almost simultaneously across the entire Earth, while others develop gradually. They can last for several hours or even days. Magnetic storms often occur 1-2 days after a solar flare due to the Earth passing through a stream of particles ejected by the Sun. Based on the delay time, the speed of such a corpuscular flow is estimated at several million km/h.
During strong magnetic storms, the normal operation of the telegraph, telephone and radio is disrupted.
Magnetic storms are often observed at latitude 66-67° (in the aurora zone) and occur simultaneously with auroras.
The structure of the Earth's magnetic field varies depending on the latitude of the area. The permeability of the magnetic field increases towards the poles. Over the polar regions, the magnetic field lines are more or less perpendicular to the earth's surface and have a funnel-shaped configuration. Through them, part of the solar wind from the dayside penetrates into the magnetosphere and then into the upper atmosphere. During magnetic storms, particles from the tail part of the magnetosphere rush here, reaching the boundaries of the upper atmosphere in the high latitudes of the Northern and Southern hemispheres. It is these charged particles that cause the auroras here.
So, magnetic storms and daily changes in the magnetic field are explained, as we have already found out, by solar radiation. But what is the main reason that creates the permanent magnetism of the Earth? Theoretically, it was possible to prove that 99% of the Earth’s magnetic field is caused by sources hidden inside the planet. The main magnetic field is caused by sources located in the depths of the Earth. They can be roughly divided into two groups. The main part of them is associated with processes in the earth's core, where, due to continuous and regular movements of electrically conductive matter, a system of electric currents is created. The other is due to the fact that rocks earth's crust, magnetized by the main electric field(field of the core), create their own magnetic field, which is summed with the magnetic field of the core.
In addition to the magnetic field around the Earth, there are other fields: a) gravitational; b) electric; c) thermal.
Gravitational field The earth is called the gravity field. It is directed along a plumb line perpendicular to the surface of the geoid. If the Earth had the shape of an ellipsoid of revolution and masses were evenly distributed in it, then it would have a normal gravitational field. The difference between the tension of real gravitational field and theoretical - an anomaly of gravity. Various material composition, density rocks cause these anomalies. But other reasons are also possible. They can be explained by the following process - the equilibrium of the solid and relatively light earth's crust on the heavier upper mantle, where the pressure of the overlying layers is equalized. These currents cause tectonic deformations, the movement of lithospheric plates and thereby create the macrorelief of the Earth. Gravity holds the atmosphere, hydrosphere, people, animals on Earth. Gravity must be taken into account when studying processes in the geographic envelope. The term " geotropism" are called the growth movements of plant organs, which, under the influence of the force of gravity, always provide a vertical direction of growth primary root perpendicular to the surface of the Earth. Gravity biology uses plants as experimental subjects.
If gravity is not taken into account, it is impossible to calculate the initial data for launching rockets and spaceships, make gravimetric exploration of ore minerals and, finally, impossible further development astronomy, physics and other sciences.
A MAGNETIC FIELD. ELECTROMAGNETS. PERMANENT MAGNETS. EARTH'S MAGNETIC FIELD
Option 1
I (1) When electric charges are at rest, then around them...
1. electric field.
2. magnetic field.
3. electric and magnetic fields.
II (1) How are iron filings arranged in a direct current magnetic field?
1. Disorderly.
2. In straight lines along the conductor.
3. Along closed curves surrounding the conductor.
III (1) Which metals are strongly attracted by a magnet? 1. Cast iron. 2. Nickel. 3. Cobalt. 4. Steel.
IV (1) When one of the poles was brought to the magnetic needle permanent magnet, then the south pole of the arrow was pushed away. Which pole was brought up?
1. Northern. 2. South.
V (1) - A steel magnet is broken in half. Will they have magnetic properties ends A And IN at the site of the magnet break (Fig. 180)?
1. Ends A and B will not have magnetic properties.
2. The end A IN- southern.
3. The end IN will become the north magnetic pole, and A - southern.
VI (1) Steel pins are brought to the magnetic poles of the same name. How will the pins be positioned if they are released (Fig. 181)?
1. They will hang vertically. 2. The heads will attract each other. 3. The heads will push away from each other.
VII (1) What are the directions of the magnetic lines between the poles of an arc-shaped magnet (Fig. 182)?
1. From A to B. 2. From B To A.
VIII (1) Formed by like or unlike poles magnetic spectrum(Fig. 183)?
1. Same names. 2. Different names.
IX (1) Which magnetic poles are shown in Figure 184?
1. A- northern, IN- southern.
2. A - southern, IN- northern.
3. L - northern, IN- northern.
4. L - southern, IN- southern.
X (1) The north magnetic pole is located at... the geographic pole, and the south - at...
1. southern... northern. 2. northern... southern.
I (1) A metal rod was connected to the current source using wires (Fig. 185). What fields are formed around the rod when a current arises in it?
1. Electric field alone.
2. Only one magnetic field.
3. Electric and magnetic fields.
II (1) What are the magnetic field lines of a current?
1. Closed curves enclosing a conductor.
2. Curves located near the conductor.
3. Circles.
III (1) Which of the following substances is weakly attracted by a magnet?
1. Paper. 2. Steel. 3. Nickel. 4. Cast iron.
IV (1) Opposite magnetic poles..., and like...
1. attract...repel.
2. repel... attracted.
V (1) Razor blade (end A)"touched the north magnetic pole of the magnet. Will the ends of the blade then have magnetic properties (Fig. 186)?
1. They won’t.
2. The end A will become the north magnetic pole, and IN - southern.
3. The end IN will become the north magnetic pole, and A - southern.
VI (1) A magnet suspended on a thread is installed in the north-south direction. Which pole will the magnet turn to the north magnetic pole of the Earth?
1. Northern. 2. South.
VII (1) What are the directions of the magnetic lines between the poles of the magnet shown in Figure 187?
1. From A to B. 2. From IN To A.
VIII (1) The north and south poles of the magnetic needle are attracted to the end of the steel rod. Is the rod magnetized?
1. Magnetized, otherwise the arrow would not be attracted.
2. It’s impossible to say for sure.
3. The rod is not magnetized. Only one pole would be attracted to the magnetized rod.
IX (1) There is a magnetic needle at the magnetic poles
(Fig. 188). Which of these poles is north and which is south?
1. A - northern, IN - southern.
2. A - southern, IN- northern.
3. A- northern, IN- northern.
4. A - southern, IN- southern.
X (1) All steel and iron objects are magnetized in the Earth's magnetic field. What magnetic poles does the steel furnace casing have at the top and bottom in the northern hemisphere of the Earth (Fig. 189)?
1. Above is northern, below is southern.
2. Above - southern, below - northern.
3. Above and below are the south poles.
4. Above and below are the north poles.
Option3
I (1) When electric charges move, then there is (are) around them...
1. electric field.
2. magnetic field.
3. electric and magnetic fields.
II (1) How can the magnetic field of a coil be strengthened?
1. Make a coil of larger diameter.
2. Insert an iron core inside the coil.
3. Increase the current in the coil.
III (1) Which of the following substances are not attracted by a magnet at all?
1. Glass. 2. Steel. 3. Nickel. 4. Cast iron.
IV (1) Middle of magnet AB does not attract iron filings (Fig. 190). The magnet is broken into two parts along the line AB, Will the ends of AB at the break point of the magnet attract iron filings?
1. There will be, but very weakly.
2. They won't.
3. They will, since a magnet with south and north poles is formed.
V (1) Two pins were brought to the magnetic pole. How will the pins be positioned if they are released (Fig. 191)?
1. They will hang vertically.
2. They will be attracted to each other.
3. Pull away from each other
VI (1) How are the magnetic lines directed between the poles of the magnet shown in Figure 192.
1 From A to IN. 2 From B to A.
VII (1) What magnetic poles form the spectrum shown in Figure 193.
1. Same name 2 Different name
VIII (1) Figure 194 shows an arc-shaped magnet and its magnetic field. Which pole is north and which is south?
1. A - northern, IN- southern.
2. A- southern, IN- northern.
3. L - northern, IN - northern.
4. L - southern, IN- southern.
IX (1) If a steel rod is placed along the Earth's meridian and struck several times with a hammer, it will become magnetized. Which magnetic pole is formed at the end facing north?
1. Northern. 2. South.
Option 4
I (1) When a metal rod was connected to one of the poles of the current source (Fig. 195), then... a field was formed around it.
1. electric
2. magnetic
3 electric and magnetic
II (1) When the current in the coil changes, does the magnetic field change?
1. The magnetic field does not change.
2. As the current increases, the effect of the magnetic field increases.
3. As the current increases, the effect of the magnetic field weakens.
III (1) Which of the following substances are attracted well by a magnet?
1 Wood. 2. Steel. 3. Nickel. 4 Cast iron
IV (1) They brought it to the iron rod magnet north pole. Which pole is formed at the opposite end of the rod?
1. 
Northern. 2. South.
(1) The steel magnet was broken into three parts (Fig. 196). Will ends A and B be magnetic?
1. They won’t.
2. The end A has a north magnetic pole IN- southern.
3. The end IN has a north magnetic pole.
A- southern.
VI (1) The end of the blade of a penknife is brought to the south pole of the magnetic needle. This pole is attracted to the knife. Was the knife magnetized?
 |
The knife was magnetized.
The end of the knife had a north magnetic pole
2 It’s impossible to say for sure.
3 The knife is magnetized, the south magnetic pole is brought up.
VII (1) In what direction will the northern end of the magnetic needle turn if it is brought into the magnetic field shown in Figure 197?
1. From A cat IN to L.
VIII (I) Which magnetic poles form the spectrum shown in Figure 198, like or unlike?
1 Same name. 2. Different names. 3. A pair of north poles. 4. A pair of south poles.
IX (1) Figure 199 shows a strip magnet AB and its magnetic field. Which pole is north and which is south?
1. A - northern. IN- southern.
2. A- southern, IN - northern.
X (1) Which pole of the magnetic needle will be attracted to the top of the school steel tripod in the northern hemisphere of the Earth. Which pole will be attracted from below (Fig. 200)?
1. The northern one will be attracted from above, and the southern one from below.
2. The southern one will be attracted from above, and the northern one from below.
3. The south pole of the magnetic needle will be attracted from above and below.
4. The north pole of the magnetic needle will be attracted from above and below.
There are two north poles on Earth (geographical and magnetic), both of which are located in the Arctic region.
Geographic North Pole
The northernmost point on the Earth's surface is the geographic North Pole, also known as True North. It is located at 90º north latitude, but has no specific line of longitude since all meridians converge at the poles. The Earth's axis connects north and, and is a conventional line around which our planet rotates.
The geographic North Pole is located approximately 725 km (450 miles) north of Greenland, in the middle of the North Pole Arctic Ocean, the depth of which at this point is 4087 meters. Most Since then, the North Pole has been covered in sea ice, but recently water has been spotted around the exact location of the pole.
All points are south! If you're standing at the North Pole, all points are south of you (east and west don't matter at the North Pole). While a complete rotation of the Earth occurs in 24 hours, the planet's rotation speed decreases as it moves away from, where it is about 1670 km per hour, and at the North Pole, there is virtually no rotation.
The lines of longitude (meridians) that define our time zones are so close to the North Pole that time zones have no meaning. Thus, the Arctic region uses the UTC (Coordinated Universal Time) standard to determine local time.
Due to the tilt earth's axis The North Pole experiences six months of 24-hour daylight from March 21 to September 21 and six months of darkness from September 21 to March 21.
Magnetic North Pole
Located approximately 400 km (250 miles) south of the true North Pole, and as of 2017 lies within latitude 86.5°N and longitude 172.6°W.
This place is not fixed and is constantly moving, even on a daily basis. The Earth's Magnetic North Pole is the center of the planet's magnetic field and the point at which conventional magnetic compasses point. The compass is also subject to magnetic declination, which is a result of changes in the Earth's magnetic field.
Due to the constant shifts of the magnetic North Pole and the planet's magnetic field, when using a magnetic compass for navigation, it is necessary to understand the difference between magnetic north and true north.
The magnetic pole was first identified in 1831, hundreds of kilometers from its current location. Canada's National Geomagnetic Program monitors the movement of the magnetic North Pole.
The magnetic North Pole is constantly moving. Every day there is an elliptical movement of the magnetic pole approximately 80 km from its center point. On average, it moves approximately 55-60 km every year.
Who was the first to reach the North Pole?
Robert Peary, his partner Matthew Henson and four Inuit are believed to be the first people to reach the geographic North Pole on April 9, 1909 (although many speculate that they missed the exact North Pole by several kilometers).
In 1958, the United States nuclear submarine Nautilus was the first ship to cross the North Pole. Today, dozens of planes fly over the North Pole, flying between continents.