Materials can be classified, according to their magnetic properties, into three types: ferromagnetic, diamagnetic and paramagnetic.
- diamagnetic: These are materials that, if placed in the presence of an external magnetic field, establish a magnetic field in their atoms in the opposite direction to that which was submitted, but which disappears as soon as the external field is removed. Due to this behavior, this type of material is not attracted to magnets. Examples are mercury, gold, bismuth, lead, silver, etc.
- Paramagnetic : This group includes materials that have unpaired electrons, which, when subjected to an external magnetic field, are aligned in the same direction as the field to which they were subjected, which disappear as soon as the external field is removed. These are objects that are weakly attracted to magnets, such as aluminum, sodium, magnesium, calcium, etc.
- Ferromagnetic : when these materials are subjected to an external magnetic field, they acquire a magnetic field in the same direction as the field to which they were subjected, which remains when the material is removed. It is as if they possess a magnetic memory. They are attracted to magnets, and this behavior is observed in a few substances, among them: iron, nickel, cobalt and some of their compounds.
