Magnetic forces occur in a magnetic field. It transfers the forces applied by magnets and affects objects in its surroundings. A magnetic field is created through the movement of electric charges. This can can be triggered by an electrical current, the temporal change of an electric field or materials that have already been magnetised, such as permanent magnets.
Humans can only sense magnetic fields indirectly. It can be recognised by the behaviour of magnetised objects in its sphere of influence. Iron filings spread out around the magnet also make it visible. The filings align themselves parallel to the field lines and thereby reveal the magnetic field.
The strength, direction and/or sense of direction of the fields can also be determined using the field lines. The greater the proximity of the field lines, the stronger the magnetic field. The force that is applied to a body runs tangential to the field line. Magnetic field lines always run from the north pole of a magnet to its south pole.
Magnetic fields always apply forces to moving loads as well as magnets and objects that can be magnetised. They are also the key to the alignment and the poles of such objects. Opposite poles attract, like poles repel each other. This basic rule ensures movement in the magnetic field because magnets always want to align themselves in a way that their opposite poles attract each other.
A very well know magnetic field is the magnetic field of our earth. On the one hand, it protects us from the charged particles of solar winds and, one the other hand, it serves as a guide for many animals, e.g. migratory birds.