What is the source of the magnetic field? The source of the Earth's magnetic field

A magnetic field is a very interesting phenomenon. Currently, its properties have found application in many areas. Do you know what is the source of the magnetic field? After reading the article, you will learn about it. In addition, we will talk about some facts related to magnetism. Let's start with history.

A bit of history

Magnetism and electricity are not two different phenomena, as they have been mistaken for a long time. Their relationship became understandable only in 1820, when the Danish scientist Hans Christian Oersted (1777-1851) showed that the current flowing through the wire deflects the compass needle. Current always creates a magnetic field. It does not matter where it flows - between the cloud and the ground in the form of lightning or in the muscle of our body.

Even in ancient times, people tried to find out what is the source of the magnetic field. Moreover, the discoveries made were applied in practice. Magnetism was observed and used (especially for navigation purposes) thousands of years before the nature of electricity was clarified and it found practical application. Only when it became known that the substance consists of atoms, it was finally established that magnetism and electricity are interrelated. Wherever magnetism is observed, there must always be some kind of electric current. However, this discovery was only the beginning of new research.

What determines the manifestation of the magnetic properties of materials in the absence of any external source of current? The motion of electrons creating electrical currents inside atoms. We will consider this type of magnetism here. The source of the vortex magnetic field (alternating current) was briefly characterized.

Magnetite and other materials

The property of attracting iron and iron-containing materials is observed in nature in one interesting mineral. It's about magnetite, one of the chemical compounds of iron. Probably, some of its variety was used in the first compasses invented by the Chinese. The source of the magnetic field is not only this mineral. It is also relatively easy for some materials to communicate the necessary properties intentionally. Among them, iron and steel are most known. Both of these materials easily become a source of magnetic field.

Permanent Magnets

Materials attracting iron form a special class. They are called permanent magnets. Despite the name, they are able to preserve the necessary properties only for a limited time. A permanent magnet in the form of a bar demonstrates the strength of terrestrial magnetism. If it can move freely, then one end of it always turns in the direction of the North Pole of the Earth, and the other - in the direction of the South Pole . The two ends of the magnet are called the north and south poles respectively.

Magnets can have almost any shape: a bar, a horseshoe, a ring or a more complex one. They are used in electrical appliances. The poles of the magnets are N (northern) and S (southern). Let's talk about how they interact.

Attraction and repulsion

Different magnetic poles are attracted. We already know this from school. Attracting some other material, the magnet first turns it into a weak magnet. The poles of the same name repel (although this is not so obvious as attraction). While testing the effect of the magnet, iron and steel themselves become magnets, acquiring the opposite polarity. That's why they are attracted to it. But if two identical magnets with equal "charges" are set close to each other with the same poles, what will happen? The observed repulsive force will be equal to the force of attraction that operates between two opposite poles, set at the same distance from each other.

Not only iron-containing materials are affected by the influence of magnetism. However, magnetic phenomena are most easily observed in pure metals. This, for example, iron, nickel, cobalt.

Domains

Metals that can become a source of magnetic field, consist of small magnets, located randomly inside the substance. They are equally oriented only on small areas, called domains, which can be seen through an electron microscope. In an unmagnetized substance - since the domains themselves are also oriented there in different directions - the magnetic field is zero. Consequently, no magnetic properties are observed in this case. Thus, the substance acquires the necessary properties only under certain conditions.

The process of magnetization consists in the fact that all domains are forced to line up in one direction. When they are properly rotated, their actions are added up. The substance as a whole becomes the source of the magnetic field. If all the domains are lined up exactly in one direction, the material reaches the limit of its magnetic abilities. One important regularity should be noted. The magnetization of the material ultimately depends on the magnetization of the domains. And it, in turn, is determined by how separate atoms are located inside the domains.

Earth's magnetic field

The magnetic field of the Earth has long been accurately measured and described, but so far it has not been fully explained. Very simplistically, it can be imagined as if a simple flat magnet is located between the North and South geographical poles. This causes some of the observed effects. But this does not explain either the very unusual changes in the intensity or even the direction of the magnetic field lines above the earth's surface, nor why millions of years ago the location of the magnetic poles was opposite to the current one, nor why they, although slowly, are constantly moving. So, everything is somewhat more complicated.

Model of the Earth's magnetic field

Let us describe in some detail its simplified version. Let us imagine in the center of the Earth a long flat magnet that will be the source of the magnetic field. What else needs to be considered? Magnetic substances on the surface of the globe should be located so that their north-facing pole turns to the side we call the north (actually to the south pole of the imaginary magnet) and the other pole to the south (the north pole of the magnet).

Understanding complex physical processes causes some difficulties. Both terrestrial magnetism and the magnetism of small pieces of iron are easier to explain, suggesting that magnetic lines of force (often referred to as magnetic flux lines ) emanate from the north end of the magnet, and enter the southern end of the magnet. This is a very arbitrary representation, applied only for the sake of convenience, just as the latitude and longitude lines drawn on the map are used. However, it helps us understand what is the source of the Earth's magnetic field.

The lines of a simple flat magnet, passing from one pole to the other and covering the entire magnet, form something like a cylinder. Force lines of the same direction seem to repel. They always start at the pole of one type and end in a pole of another type and never intersect.

Finally

So, we opened the topic "The source of the magnetic field." As you can see, it is quite extensive. We have considered only the basic concepts relating to this topic.