One of the most important physical characteristics of both the natural and the artificial human environment is the magnetic field. It represents one of the forms of existence of an electromagnetic field. The main distinguishing feature of this form is that the magnetic field acts exclusively on those particles and bodies that, on the one hand, are in continuous motion, and on the other hand, contain a certain electric charge.
It is also known from the physics course that to create a magnetic field, a current conductor and alternating electric fields are needed. The most important characteristics of this field are the magnetic induction vector and magnetic intensity.
The magnetic field strength is one of the vector quantities studied in physics, which consists of the difference of the electromagnetic induction vector, as well as the magnetization vector. Since magnetic tension is a vector quantity, it is customary to consider ampere per meter as its unit of measurement in the generally accepted and most common SI system . In order to obtain an electromagnetic field strength of 1 a / m, it is necessary that an electric current of 2π amperes flow in a straight, long wire with a maximum small cross-sectional diameter. In this case, at all points of the magnetic field formed by this current at a distance of 1 meter, the electromagnetic field strength will be equal to 1 a / m.
The magnetic field strength, or, in other words, the number of lines of force of this field, can be estimated. In particular, to determine the direction of these lines, you can use the well-known rule of the gimlet. This rule is one of the cornerstones of all electrical engineering. It says that if the general direction of movement of the gimlet is completely identical to the direction of electric current in a particular conductor, then the direction of rotation of the gimlet is identical to the direction of magnetic lines.
Based on this rule, it is easy to prove that the magnetic lines that arise in the turns of the coil are directed in the same direction. From this we can conclude that the magnetic field inside the coil will be much stronger than the tension created by one turn. This is due, inter alia, to the fact that the lines of force of the neighboring turns are directed parallel to each other, but in different directions, therefore, the magnetic field strength between them will steadily decrease.
It is natural that the magnetic field of any coil is directly proportional to the magnitude of the current flowing through its turns. In addition, the magnetic field directly depends on how close these turns are located in relation to each other. It has been experimentally proved that in two coils in which an electric current of the same strength flows, and the number of turns coincides, the magnetic field will be stronger in the one where the coil has a shorter axial length, that is, its turns are much closer to each other.
A very significant characteristic of the magnetic field is the numerical value of ampere-turns, which can be calculated by multiplying the number of turns in the coil by the strength of the current flowing in them. Magnetomotive force will also depend on the magnitude of the ampere-turns. Based on this concept, one can easily prove that the magnetic field of the studied coil is in direct proportion to the number of ampere-turns per unit axial length. In other words, the electromagnetic field intensity is higher, the greater the magnitude of the magnetomotive force created in the studied coil.
In addition to artificially created magnetic fields, there is also a natural magnetic field of the Earth, which is formed mainly in the outer shell of the core. The main characteristics of this field, including intensity, change both in time and in space, however, all the basic laws characteristic of artificially created fields also work in a geomagnetic field.