Magnetism

Simply explained, magnetism is an invisible physical force that acts on matter or substances such as iron. In the field of physics, the term encompasses all sub-areas that study magnets and magnetic fields. Research into magnetism therefore examines the properties of magnets (for example attraction or repulsion) and the phenomena associated with them. In physics, the Tesla (unit) is used as a unit of measurement for magnetism.

A brief history of magnetism

Natural magnets consist of iron, oxygen and iron hydroxide and are formed naturally through volcanism. Magnetism has been used profitably at least since the invention of the compass – around 1100.

The first systematic experiments to determine magnetic force were not carried out before 1269. Pierre de Maricourt investigated when magnetic poles attract or repel each other and recorded his results. These experiments formed the foundation on which magnetism research was built in later years.

Interesting fact: light and magnetism are also related, because strictly speaking, light is made up of vibrating, electric and magnetic fields.

First introduction to magnetism: The basics

Much of magnetism is taught in elementary school. A magnet basically has two poles: the north pole (usually shown in red) and the south pole (normally blue). Outside the magnet, the field lines always run from the north pole to the south pole, in three dimensions. Simply explained, a magnet gets its power from these movements (or electrical currents). The field lines graphically represent the magnetism, i.e. the power of the magnet and its strength.

An object must be within this field so that the magnet can influence it. Individual areas of physics study different types of magnets and magnetism, including:

  • Magnetites (manifestation of magnetism in nature)
  • Permanent or permanent magnets (e.g. bar magnets)
  • Temporary magnets
  • Electromagnets

Iron oxide, samarium, cobalt and neodymium are usually used to create permanent magnets and generate magnetism. neodymium magnets are among the strongest magnets in the world and have a remarkable lifespan. It is estimated that they lose only about 5% of their magnetism every 100 years. However, if they are incorrectly stored or exposed to high temperatures, they can lose their magnetic effect. This is the case at around 80°C. However, there are special exceptions that can also tolerate higher temperatures.

Electromagnets consist mainly of copper coils. Nowadays it is possible to produce strong electromagnets artificially by passing electricity through coils. A magnetic field then forms around each conductor through which the current flows, and this is referred to as the effect of electrical magnetism. Overheating problems that can arise from magnetism and electricity can be avoided with the help of superconductors.

What types of magnetism are there?

To describe the magnetic properties of individual materials, a distinction is made between three categories:

  • Diamagnetism: The material has no magnetic effect and is even slightly repelled.
  • Paramagnetism: The material is only weakly attracted.
  • Ferromagnetism: The Material is exposed to a strong magnetic attraction.

Magnets only work on certain magnetizable raw materials - more precisely on ferromagnetic materials such as:

  • Iron
  • Steel
  • Nickel
  • Cobalt

If a non magnetized ferromagnet comes into contact with an external field and this is then switched off, the ferromagnet retains a positive or negative magnetization. In such cases, the magnetism causes what is known as hysteresis (change in effect after a change in cause). The negative or positive magnetization that remains after this process is also called remanent magnetism in physics.

Info: Shielding from magnetism is also possible. With magnetic shielding, field lines are redirected by certain materials or excluded from areas. Examples include MU metals, soft iron and Vitroperm.

Applications of magnetism in everyday life

Today, magnetism is not only omnipresent in physics. In everyday life we find magnets in all possible shapes and places, including:
  • Motor vehicles
  • Hard drives
  • Current transformers
  • Construction site equipment

Strong magnetic fields enable the study of materials at the atomic level. In combination with spins, doctors use magnetic resonance imaging (MRI for short) to examine internal organs and tissue structures. Furthermore, magnetic forces can be converted into electrical forces - and vice versa.

While the position of electrons influences the magnetic properties of a material, the movement of electrons in one direction generates electricity. Therefore, magnetism also plays an important role in the field of electrical engineering. For example, engineers have used magnetic levitation to build high-speed trains such as the Transrapid magnetic levitation train.

As a field of research in physics, magnetism also provides explanations for how planets move in space. In principle, our Earth is a giant magnet: it has a north and south pole and is surrounded by a natural geomagnetic field. The orientation of the magnetic field of the earth explains why the needle on a compass always points north.


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