Mutual inductance and mutual inductance electromotive force
If the mutual inductance phenomenon shown on the right is two a transformer coupling coil two adjacent 1 and 2, respectively with current I1 and I2, part of I1 excitation magnetic field through the magnetic coil 2, here we use magnetic flux Phi 12 said, when the current I1 coil 1 changes, through the 2 of the 12 coil flux will change, so the coil 2 induced electromotive force (EMF E12 magnetic flux through the coil the change); similarly, when the current I2 coil changes, flux of magnetic field coil I2 generated 1 of the 21 changes. The 1 coil will produce electromotive force e21;
The electromagnetic induction phenomenon caused by the change of current in one coil and in another coil is called the mutual inductance phenomenon, and the electromotive force generated is called mutual inductance electromotive force.
Transformer electromotive force E12 with other EMF, flux rate is proportional to the rate of change of magnetic flux through the coil and 2 (delta front said that this is a change of volume). But in a 12 proportional to I1, delta phi 12 with delta are proportional to I1. As a result, the change rate of e12= magnetic flux is proportional to the mutual inductance, that is, the size of the mutual inductance electromotive force E12 can be expressed as:
Electromotive force of mutual inductance
In the same way, due to the change of the current I2 in the coil 2, the size of the mutual inductance electromotive force E21 produced in the loop 1 can be expressed as the size of the electric potential.
Coils mutual inductance electromotive force
The direction of E12 and E21 can be determined by Lenz's law.
Mutual inductance coefficient
In the above mutual inductance electromotive force E12 formula, M12 is called the mutual inductance coefficient of coil 1 to coil 2; the M21 in the back E21 formula is called the mutual inductance coefficient of coil 2 to coil 1. It can be shown that, M12=M21 and M, M is called the mutual inductance of the two coils. That is:
Mutual inductance coefficient
Mutual inductance is referred to as mutual inductance, and its unit is the same as self inductance. It is Henry, abbreviated as Henry, and the international symbol is H. Its size depends on the geometry, size, relative position of the two coils, the number of turns, and the permeability of the media around them. The calculation of mutual inductance M is usually complex and often measured by experimental method.
Application of mutual inductance phenomenon
Mutual inductance is widely applied in electrical and electronic technology. By means of mutual inductance and coil, energy or signal can be easily transferred from one coil to another coil, making use of the principle of mutual inductance to make transformer, induction coil and so on.
The phenomenon of mutual inductance can also have adverse effects in some cases, for example, cable phones often cause crosstalk because of mutual inductance between the telephone. In the electronic circuit, due to the improper arrangement of the coil position, or the mutual inductance between wires and components, causing interference or even the circuit can not work normally, we should try to reduce mutual inductance coupling in this case. For example, the distance between the coils is increased or the two coil is vertically placed. In some special cases, the coil or other elements can be shielded with ferromagnetic materials to eliminate the harmful effects of mutual inductance.