## graphic representation of the magnetic field

magnetic field is invisible in nature.For convenience, a method was developed the graphical images in the form of power lines.Their direction must coincide with the direction of the magnetic field strength.Power lines have no beginning or end they are closed.This reflects one of the Maxwell equations in the theory of the electromagnetic interaction.The scientific community accepted that the lines of force "begin" at the north pole of the magnet and the "end" in the south.This addition was made solely for the conditional setting direction of the vector magnetic field strength.

in a closed magnetic field lines can be seen with a simple experiment.It should be sprinkled with a permanent magnet, and the area around it with iron filings.They will
be arranged in such a way that you can see for yourself the power line.

## The magnetic field

magnetic field vector is the same vector as described in the previous section.That it should be the same direction with the direction of the field lines.This is the power with which the field acts on the permanent magnet is placed in it.The tension characterizes the interaction of the magnetic field from the surrounding material.There is a special formula, which can be used to determine its unit vector in every point in space (the law of Biot-Savart-Laplace).The intensity does not depend on the magnetic properties of the medium and is measured in oersteds (CGS system) and A / m (SI).

## induction of the magnetic field and the magnetic flux

magnetic induction describes its intensity, ie,the ability to produce work.The higher this capacity, the stronger the field and the higher the concentration of the lines of force of 1 m2.Magnetic flux is the product of induction in the area, which affects the field.Numerically, this value is accepted equal to the number of power lines running through a certain area.The flow is maximal if the site is located perpendicular to the direction of the vector of tension.The smaller the angle, the less impact.

## permeability

action of a magnetic field in a particular environment depends on its permeability.This value characterizes the induction medium.Air and some substances have a magnetic permeability of free space (value is taken from the tables of physical constants).In ferromagnets, it is a thousand times more.