Magnetism is generally understood as an invisible physical force that acts on matter. In the field of physics, the term summarizes all areas that study magnets and magnetic fields. Accordingly, research on magnetism examines the properties of magnets (for example, attraction or repulsion) and the phenomena that are associated with them. The Tesla is used as the unit of measurement for magnetism.
First introduction to magnetism
A magnet basically has two poles: the north pole (usually shown in red) and the south pole (usually in blue). Outside the magnet, the field lines always run from the North Pole to the South Pole, in three dimensions alone. An object must be within this field so that the magnet can influence it. Individual areas of physics examine different types of magnetism, including:
- Magnetite (manifestation of magnetism in nature)
- Permanent or permanent magnets (e.g. rod magnets)
- Temporary magnets
Iron oxide, samarium, cobalt and neodymium
are usually used to create permanent magnets. Electromagnets mainly consist of copper coils. Nowadays it is possible to artificially manufacture extremely strong electromagnets. Overheating problems that can arise from magnetism can be avoided with the help of superconductors
Forms of magnetism in physics
There are three categories to describe the magnetic properties of individual materials:
- Diamagnetism: The fabric has no magnetic effect and is even slightly repelled.
- Paramagnetism: The fabric is only slightly attracted.
- Ferromagnetism: The fabric is very attractive.
Magnets only act on certain raw materials, more precisely on ferromagnetic materials
If a non-magnetized ferromagnet comes into contact with an external field and this then switches off, the ferromagnet retains a positive or negative magnetization
. In such cases, magnetism causes a so-called hysteresis
(change in effect after changing the cause). The negative or positive magnetization that remains during this process is also called retentive magnetism
Applications of magnetism in everyday life
Nowadays magnetism is not only omnipresent in physics. In everyday life we find magnets in all possible places, including:
- Motor vehicles
- Hard drives
- Power converter
- Construction site equipment
Strong magnetic fields
enable the research of matter at the atomic level. For example, doctors use magnetic resonance imaging
(MRI) to examine internal organs and tissue structures. Furthermore, magnetic forces can be converted into electrical forces - and vice versa. While the position of electrons affects the magnetic properties of a material, the movement of electrons in turn 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 like the Trans rapid maglev train.
As a research area of physics, magnetism also provides explanations of how planets move in space. In principle, our earth is a huge magnet: it has a north or south pole and is surrounded by a natural earth's magnetic field. This explains why the needle on a compass always points north.