What is the magnetic field lines

No doubt, the lines of force of the magnetic field are now known to everyone. At least, even in school, their manifestation is demonstrated in physics lessons. Do you remember how the teacher placed a permanent magnet (or even two, combining the orientation of their poles) under the sheet of paper, and metal sawdust, taken from the labor study room, was placed on top of it? It is understandable that the metal had to be held on the sheet, but something strange was observed - lines clearly visible along which sawdusts were built. Notice - not evenly, but in stripes. These are the lines of force of the magnetic field. Rather, their manifestation. What happened then and how can you explain it?

Let's start from afar. Together with us, in the physical world of the visible, a special kind of matter coexists - a magnetic field. It ensures the interaction of moving elementary particles or larger bodies that have an electric charge or a natural magnetic moment. Electrical and magnetic phenomena are not only interconnected with each other, but also often generate themselves. For example, a wire through which an electric current flows creates around itself lines of the magnetic field. The converse is also true: the effect of alternating magnetic fields on a closed conducting circuit creates a motion of charge carriers in it. The latter property is used in generators supplying electrical energy to all consumers. A bright example of electromagnetic fields is light.

The magnetic field lines around the conductor rotate, or, which is also true, characterized by a directed vector of magnetic induction. Direction of rotation is determined by the rule of the drill. The lines indicated are conventional, since the field extends uniformly in all directions. The thing is that it can be represented in the form of an infinite number of lines, some of which have a more pronounced tension. That is why in the experiment with a magnet and sawdust, certain "lines" are clearly traced. Interestingly, the magnetic field lines are never interrupted, so it's impossible to say unequivocally where the beginning is, and where the end is.

In the case of a permanent magnet (or similar electromagnet), there are always two poles, which have the conventional names of the North and South. The lines mentioned in this case are rings and ovals connecting both poles. Sometimes this is described from the point of view of interacting monopoles, but then a contradiction arises, according to which it is impossible to separate the monopoly. That is, any attempt to divide the magnet will lead to the appearance of several bipolar parts.

Of great interest are the properties of lines of force. We have already talked about continuity, but of practical interest is the ability to create in the conductor an electromotive force (EMF), the consequence of which is an electric current. The meaning of this is as follows: if the conducting contour crosses the magnetic field strength lines (or the conductor itself moves in a magnetic field), then additional electrons are imparted to the electrons in the outer orbits of the atoms of the material, allowing them to start an independent directed motion. It can be said that the magnetic field "knocks out" charged particles from the crystal lattice. This phenomenon is called electromagnetic induction and is currently the main way of obtaining primary electrical energy. It was discovered experimentally in 1831 by the English physicist Michael Faraday.

The study of magnetic fields began back in 1269, when P. Peregrin discovered the interaction of a spherical magnet with steel needles. Almost 300 years later, Colchester suggested that the Earth itself is a huge magnet with two poles. Further, magnetic phenomena have been studied by such famous scientists as Lorentz, Maxwell, Ampere, Einstein, and others.