Physics

Magnets and magnets


A magnet is defined as an object capable of causing a magnetic field around it and can be natural or artificial.

A natural magnet is made of minerals with magnetic substances, such as magnetite, and an artificial magnet is made of a material without magnetic properties, but which can permanently or instantly acquire characteristics of a natural magnet.

Artificial magnets are also subdivided into: permanent, temporal or electromagnets.

  • A permanent magnet is made of material capable of maintaining magnetic properties even after the magnetization process ceases, these materials are called ferromagnetic.
  • A time magnet has magnetic properties only while under the action of another magnetic field, the materials that enable this type of process are called paramagnetic.
  • An electromagnet is a device composed of a conductor through which electric current circulates and a core, usually of iron. Its characteristics depend on the current flow through the conductor; when current flow ceases, the existence of the magnetic field also ceases.

Magnets Properties

Magnetic poles

These are the regions where the magnetic actions intensify. A magnet is composed of two magnetic poles, north and south, usually located at their ends, except when they do not exist, as in a disk-shaped magnet, for example. For this reason they are called magnetic dipoles.

In order to determine these poles, the magnet must be suspended by the center of mass and it will align approximately with the geographic north and south pole receiving equivalent nomenclature. Thus, the magnetic north pole should point to the geographic north pole and the magnetic south pole to the geographic south pole.

Attraction and repulsion

When handling two magnets we clearly realize that there are two ways to put them to be repelled and two ways to attract them. This is due to the fact that poles with the same name repel each other, but poles with different names attract each other:

This property leads us to conclude that the geographic north and south poles do not coincide with the magnetic north and south poles. In fact they are at virtually opposite points, as shown in the figure below:

The inclination of the magnetic axes relative to the geographic axes is approximately 191 °, making their poles practically inverted relative to the geographical poles.

Interaction between poles

Two poles attract or repel each other, depending on their characteristics, at the inverse ratio of the square of the distance between them. That is, if an interaction force F is established at a distance dby doubling this distance the observed force will be equal to a quarter of the previous F / 4. And so on.

Inseparability of the poles of a magnet

This property says that it is impossible to separate the magnetic poles of a magnet, since every time it is divided new poles will be obtained, so it is said that any new piece will remain a magnetic dipole.