The magnetic interaction of objects is one of the fundamental processes that govern everything in the universe. Its visible manifestations are magnetic phenomena. Among them can be called the northern lights, the attraction of magnets, magnetic storms, etc. How do they arise? What are characterized by?
Magnetism
Magnetic phenomena and properties are collectively called magnetism. Their existence was known for a very long time. It is assumed that already four thousand years ago, the Chinese used this knowledge to create a compass and navigation in sea trips. To conduct experiments and seriously study the physical magnetic phenomenon began only in the XIX century. One of the first researchers in this area is Hans Oersted.
Magnetic phenomena can occur both in space and on Earth, and appear only within the limits of magnetic fields. Such fields arise from electric charges. When the charges are stationary, an electric field is formed around them. When they move - a magnetic field.
That is, the phenomenon of a magnetic field occurs with the appearance of an electric current or an alternating electric field. This is a region of space within which a force acts, affecting magnets and magnetic conductors. It has its own direction and decreases with distance from its source - the conductor.
Magnets
The body around which a magnetic field forms is called a magnet. The smallest of them is an electron. The attraction of magnets is the most famous physical magnetic phenomenon: if you attach two magnets to each other, they will either attract or push off. The thing is in their position relative to each other. Each magnet has two poles: north and south.
Poles of the same name repel, and opposite poles are attracted. If you cut it in two, then the north and south poles will not separate. As a result, we get two magnets, each of which will also have two poles.
There are a number of materials that have magnetic properties. These include iron, cobalt, nickel, steel, etc. Among them are liquids, alloys, chemical compounds. If you hold the magnets near the magnet, then they themselves will become it.
Substances such as pure iron easily acquire a similar property, but also quickly say goodbye to it. Others (for example, steel) are magnetized longer, but hold the effect for a long time.
Magnetization
We have established above that a magnetic field occurs when charged particles move. But what kind of movement can be discussed, for example, in a piece of iron hanging on a refrigerator? All substances are composed of atoms, in which moving particles are located.
Each atom has its own magnetic field. But, in some materials, these fields are randomly directed in different directions. Because of this, one large field is not created around them. Such substances are not able to magnetize.
In other materials (iron, cobalt, nickel, steel), atoms are able to line up so that they are all directed the same way. As a result, a common magnetic field is formed around them and the body will be magnetized.
It turns out that the magnetization of the body is the ordering of the fields of its atoms. To disrupt this order, it is enough to hit him hard, for example, with a hammer. The fields of atoms will begin a chaotic motion and lose their magnetic properties. It will also happen if the material is heated.
Magnetic induction
Magnetic phenomena are associated with moving charges. So, around a conductor with an electric current a magnetic field will certainly arise. But could it be the other way around? This question was once asked by the English physicist Michael Faraday and discovered the phenomenon of magnetic induction.
He concluded that a constant field cannot cause an electric current, and an alternating one can. Current arises in a closed loop of the magnetic field and is called induction. The electromotive force will change in proportion to the change in the speed of the field that permeates the circuit.
The discovery of Faraday was a real breakthrough and brought considerable benefits to electrical manufacturers. Thanks to him, it became possible to receive current from mechanical energy. The law, deduced by the scientist, was applied and is applied in the device of electric motors, various generators, transformers, etc.
Earth's magnetic field
Jupiter, Neptune, Saturn and Uranus have a magnetic field. Our planet is no exception. In ordinary life, we practically do not notice it. It is not tangible, has no taste or smell. But it is with him that magnetic phenomena in nature are associated. Such as auroras, magnetic storms or magnetoreception in animals.
In fact, the Earth is a huge, but not very strong magnet, which has two poles that do not coincide with the geographical ones. Magnetic lines exit the planet’s South Pole and enter the North. This means that in fact the South Pole of the Earth is the north pole of the magnet (therefore, in the West the blue pole is S, and the red pole is N in red).
A magnetic field extends hundreds of kilometers from the surface of the planet. It serves as an invisible dome that reflects powerful galactic and solar radiation. During the collision of radiation particles with the Earth’s shell, many magnetic phenomena are formed. Let's look at the most famous of them.
Magnetic storms
The sun has a strong influence on our planet. It not only gives us warmth and light, but also provokes such unpleasant magnetic phenomena as storms. Their appearance is associated with an increase in solar activity and the processes that occur inside this star.
The Earth is constantly affected by the flow of ionized particles from the Sun. They move at a speed of 300-1200 km / s and are characterized as a solar wind. But from time to time on the star there are sudden emissions of a huge amount of these particles. They act on the earth’s shell like tremors and cause the magnetic field to oscillate.
Such storms usually last up to three days. At this time, some people on our planet are unwell. Fluctuations in the membrane affect us with headaches, increased pressure and weakness. Throughout life, a person experiences an average of 2000 storms.
Northern Lights
There are more pleasant magnetic phenomena in nature - the northern lights or aurora. It manifests itself in the form of a glow of the sky with rapidly changing colors, and occurs mainly in high latitudes (67–70 °). With strong activity of the Sun, radiance is observed below.
At approximately 64 kilometers above the poles, charged solar particles meet with the far boundaries of the magnetic field. Here, some of them are sent to the Earth’s magnetic poles, where they interact with atmospheric gases, which is why the radiance appears.
The spectrum of the glow depends on the composition of the air and its sparseness. The red glow occurs at an altitude of 150 to 400 kilometers. Blue and green shades are associated with a high content of oxygen and nitrogen. They occur at an altitude of 100 kilometers.
Magnetoreception
The main science studying magnetic phenomena is physics. However, some of them may affect biology. For example, the magnetosensitivity of living organisms is the ability to recognize the Earth's magnetic field.
This unique gift is possessed by many animals, especially migratory species. The ability to magnetoreception was found in bats, pigeons, turtles, cats, deer, some bacteria, etc. It helps animals navigate in space and find their home, moving away from it for tens of kilometers.
If a person uses a compass for orientation, then animals use completely natural tools. Scientists cannot yet determine exactly how and why magnetoreception works. But it is known that pigeons are able to find their home even if they are taken away from it for hundreds of kilometers, while closing the bird in an absolutely dark box. Turtles find their birthplace even years later.
Thanks to their "superpowers" animals foresee the eruption of volcanoes, earthquakes, storms and other disasters. They subtly sense fluctuations in a magnetic field, which increases the ability to self-preservation.