Magnetism: a fundamental force of nature

Magnetism is one of the four fundamental interactions in nature and describes the force exerted by magnets and moving electrical charges. Magnetism plays a central role in physics and technology and is inextricably linked to electric currents and magnetic fields. From the Earth's magnetic field to advanced technologies in medicine, magnetism is everywhere.

Origin of magnetism

Magnetism is created by the movement of electrons in atoms. Two main mechanisms are responsible for this:

• Electron spin: Electrons have a property called spin, which acts like a small magnet.
• Electron motion: Electrons orbiting the atomic nucleus also generate a magnetic field.

In most materials, these effects cancel each other out. However, in ferromagnetic materials such as iron or nickel, the magnetic moments align and create a strong magnetic field.

Types of magnetism

• Ferromagnetism: Occurs in materials such as iron, cobalt and nickel, where the magnetic domains align and reinforce each other.
• Paramagnetism: Materials such as aluminium or platinum are weakly magnetised and lose their magnetisation when the external field is removed.
• Diamagnetism: All materials exhibit a weak effect in which they are repelled by magnetic fields.
• Ferrimagnetism: Mixed magnetic moments occur in materials such as ferrites, which produce a weaker but permanent magnetisation.
• Antiferromagnetism: Here, the magnetic moments of neighbouring atoms balance each other out, resulting in no macroscopic magnetisation.

Magnetic fields and their effect

A magnetic field is the invisible area around a magnet or a current-carrying conductor in which magnetic forces act. Magnetic fields influence charged particles, ferromagnetic materials and other magnetic fields. The strength of a magnetic field is described by the magnetic flux density ( B ) in tesla (T) or by the magnetic field strength ( H ) in amperes per metre (A/m).

Magnetic fields have fascinating properties: they can force charged particles onto spiral paths, attract ferromagnetic materials or convert mechanical energy into electrical energy, as in generators.

Applications of magnetism

Magnetism is an integral part of modern technologies and has a wide range of applications:

• Electrical engineering: Electric motors, generators and transformers are based on the principles of magnetism.
• Communication: Magnetic materials are used in antennas, loudspeakers and microphones.
• Data storage: Hard drives and magnetic tapes use magnetic particles to store information.
• Medicine: Magnetic resonance imaging (MRI) provides detailed insights into the human body.
• Navigation: The Earth's magnetic field enables the use of compasses for orientation.

Magnetism in nature

Magnetism is also a natural process that can be observed on Earth and in the universe:

• Earth's magnetic field: The Earth's magnetic field protects our planet from cosmic radiation and deflects the solar wind.
• Polar lights: The interaction of charged particles with the Earth's magnetic field produces the impressive auroras in the polar regions.
• Stars and galaxies: Magnetic fields play a crucial role in astrophysical processes such as star formation or in magnetars, the strongest magnets in the universe.

Interesting facts about magnetism

Did you know that magnetism plays a crucial role in the generation of energy from renewable sources? Magnetism is used in wind and hydroelectric power plants to efficiently convert mechanical energy into electrical energy. Magnets are also the basis for superconducting materials that may enable lossless energy transmission in the future.