What is the induction of a magnetic field?To answer this question, let us recall the fundamentals of electrodynamics. As is known, a fixed charge carrier q, located in the electric field, is biased with force F. The larger the charge value (regardless of its properties), the greater the force. This is tension - one of the properties of the field. If we denote it as E, we get:
E = F / q
In turn, mobile charges are exerted byinfluence of magnetic field. However, in this case the force depends not only on the magnitude of the electric charge, but also on the vector of the direction of motion (or, more accurately, the velocity).
How can you study the configurationmagnetic field? This task was successfully solved by well-known scientists - Amper and Oersted. They placed in the field a conducting circuit with an electric current and studied the intensity of the exposure. It turned out that the result was influenced by the orientation of the contour in space, which indicated the presence of the direction vector of the moment of forces. The induction of the magnetic field (measured in Tesla) is expressed in terms of the ratio of the said moment of force to the product of the conductor area of the circuit and the flowing electric current. In fact, it characterizes the field itself, which in this case is necessary. Let's express all told through the simple formula:
B = M / (S * I);
where M is the maximum value of the moment of forces, depends on the orientation of the contour in the magnetic field; S is the total area of the circuit; I is the current value in the conductor.
Since the induction of the magnetic field isvector quantity, then it is required to find its orientation. The most graphic representation of it is given by an ordinary compass, the arrow of which always points to the north pole. The induction of the earth's magnetic field orientates it according to magnetic lines of force. The same happens when the compass is placed near a conductor, through which a current flows.
Describing the contour, we need to introduce the conceptmagnetic moment. This is a vector numerically equal to the product of S by I. Its direction is perpendicular to the conditional plane of the current-conducting circuit itself. You can determine by the well-known rule of the right screw (or gimlet, which is the same thing). The induction of the magnetic field in the vector representation coincides with the direction of the magnetic moment.
Thus, it is possible to derive a formula for the force acting on the contour (all vector quantities!):
M = B * m;
where M is the total vector of the force moment; B is the magnetic induction; m is the value of the magnetic moment.
No less interesting is the induction of the magnetic fieldsolenoid. It is a cylinder with a wound wire through which an electric current flows. It is one of the most used elements in electrical engineering. In everyday life with solenoids, each person faces constantly, without even knowing about it. So, the magnetic field created by the current inside the cylinder is completely homogeneous, and its vector is directed coaxially with the cylinder. But outside the cylinder body there is no magnetic induction vector (equal to zero). However, this is true only for an ideal solenoid with infinite length. In practice, however, the restriction makes its own adjustments. First of all, the induction vector is never equated to zero (the field is registered around the cylinder), and the internal configuration also loses its homogeneity. Why then do we need an "ideal model"? Very simple! If the diameter of the cylinder is less than the length (as a rule, it is), then in the center of the solenoid, the induction vector practically coincides with this characteristic of the ideal model. Knowing the diameter and length of the cylinder, it is possible to calculate the difference between the induction of a finite solenoid and its ideal (infinite) colleague. Usually it is expressed as a percentage.
