What is a magnet?

We explain what a magnet is, what its characteristics are and how they work. In addition, its classification, magnetic field and applications.

1. What is a magnet?

A body of any material capable of producing a magnetic field and attracting itself or being attracted to another magnet or to any other body of iron, cobalt or other ferromagnetic metals is known as a magnet . It is a material with natural or artificial ferromagnetic properties, which generate a continuous magnetic field.

The magnets are some of the first manifestations that the human being  discovered of magnetism , known since classical antiquity but understood only in the nineteenth century , when it was learned that most of the known elements and compounds demonstrated a certain level of magnetism. Today it is also known that certain uses of electricity can also generate magnetic fields, in what is known as an electromagnet.

2. Characteristics of a magnet

Magnets are magnetically charged bodies, which generate a magnetic field around them  based on two poles: negative (South) and positive (North) . These poles attract with their opposites (positive-negative) but repel their peers (positive-positive or negative-negative). The line that joins both poles is called the magnetic axis.

The magnetic properties of the magnets remain intact unless they are applied by opposing magnetic forces, they are increased in temperature (above the Curie Temperature or Curie Point, different depending on the element), or if subjected to shocks Strong or high. On the other hand, these properties can be temporarily transferred to a sensitive material , by contact (magnetization).

3. How do magnets work?

The magnetism of the magnets is the product of a particular arrangement of the electrons ( subatomic particles with negative charge) that make up the matter, which are aligned around the same direction, leading to a uniform electrical flow. For this reason, the introduction of energy into matter (intense magnetism of the opposite type or heat that greatly raises the temperature) destroys the magnetism, since it alters the delicate balance of electrons .

In the case of induced magnets (magnetized substances) the effect is similar: when subjected to a magnetic field by contact, their electrons are ordered in the same direction and reproduce the magnetic field for some time.

4. Types of magnets

There are three types of magnets, classified according to their nature in:

• Natural magnets Generally composed of mixtures of magnetite (ferrofelite or morpholite, composed of ferric oxides) and other terrestrial minerals, they naturally possess their magnetic properties. The main deposits of magnetite are found in Sweden (Falun, Dalarna province), Norway (Arendal), France (Plestin-les-Gréves, Brittany) and Portugal (Sao Bartolomé, Nazaré).
• Permanent artificial magnets. Materials sensitive to magnetism that, after being rubbed with magnetite, replicate their ferromagnetic properties for a long period of time until eventually lost.
• Temporary artificial magnets. Materials sensitive to magnetism that, after being rubbed with magnetite, replicate their ferromagnetic properties, only for a very short period of time.
• Electromagnets They are coils through which electricity circulates, generating an electric field around it that also has magnetic properties. These properties will last only as long as electricity circulates and will be lost very quickly over time.

5. Magnetic field of a magnet

A magnetic field is the region of space around a magnet in which its magnetic forces manifest and act, interacting (attracting or repelling) ferromagnetic objects and other magnets that are within the field.

It is usually represented by force lines , which are curved arrows that indicate the vector direction of the magnetic force of the field. The shape and direction of these lines will depend on the shape of the magnet, and have their greatest intensity in the region of the poles.

Our planet Earth has a magnetic field similar to that of magnets , since its cast iron core allows it to create a magnetosphere around it. For that reason the compass needles are aligned with the north pole. This magnetic field also defends us from solar electromagnetic emissions, known as “solar wind.”

6. Magnet applications

Magnets have played various roles in our civilization since ancient times and today they are an indispensable element in electronics and electricity. Some of its best known applications are:

• Manufacture of magnetic tapes. In the electronics and computer industry , magnetism allows the storage of information through iron oxides whose particles, susceptible to ordering by the magnetic field, can be read with the binary code.
• Electric transformers. Using coils and electromagnets, the electrical current can be modulated to quickly change the electromagnetic fields. This principle is fundamental in modern electrical transmission and also applies to radios, speakers and other devices.
• AC motors. These motors are a type of electromagnet, since rotating magnets mobilize the rotors with their magnetic fields.
• Magnetic suspension Large and powerful magnets are used in the magnetic suspension of trains and other vehicles, as well as in industrial magnetic cranes.
• Craft use The magnets are usually attached to various handicrafts or tourist souvenirs for sale, under the premise that when they return home tourists will place it on the metal surface of their refrigerator.