Magnets - What are they?

I often wondered why magnets attract and repel. This has fascinated me for a long time. I have research four interesting facts and uses of magnets. First a little bit about the science of magnets.

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This phenomenon is caused by an object-generated magnetic field. A magnet has two places (poles) where the magnet action is the strongest and is therefore also called dipole. The magnetic field indicates a freely suspended magnet to the geomagnetic north pole. That place on the magnet is called the north pole. I would like focus more on the uses of magnets.
Magnetic materials include iron, nickel and cobalt. They consist of magnetic atoms, which derive their magnetic property from two electrons with a parallel spin.

The direction and strength of magnetic forces can be seen by means of field lines. A magnet causes a magnetic field and is also flowed through this magnetic field. The surfaces crossed by the vast majority of the magnetic field are called the poles of the magnet.

Earth's Magnetic Field

The earth's magnetic field penetrates and surrounds the earth. It consists of three components. The main part of the magnetic field (about 95%) is derived from the so-called geodynamo in the liquid outer earth core. It is subject to slow temporal changes, typically lasting many 10,000 years. Over long periods of time, it has approximately the form of a magnetic dipole on the earth's surface, slightly oblique to the earth's axis. In between are geomagnetic excursions on a time scale of centuries, which can lead to pole jumps. The main component of the earth's magnetic field is this slowly changing dipole component at the level of several decades.

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Migration of Birds

The "inner compass" is presumably the result of a magnetin, more specifically of magnetic field receptors, with the help of which the birds can perceive the inclination angle of the earth's magnetic field. In the case of robins, this receptor is clearly located in the right eye: If the eye is covered, it loses its ability to orient in the earth's magnetic field. In pigeons, it was shown that a magnetic sensor is located at the upper part of the beak. It could measure the strength of the magnetic field.

According to a study, electrosmog affects the magnetic compass of the migratory birds in the frequency range from two kilohertz to five megahertz. This relatively low frequency range can already be found in normal household appliances. If the birds have moved away from the electrosmog area, they can easily orient themselves to the magnetic field of the earth.

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Magnetic Levitation Trains

Magnetic levitation trains are tracked land transport vehicles that are suspended, driven, and braked by magnetic forces. The technology allows high speeds, accelerations and gradients, but has not been accepted by the market.

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Ferrofluids

Ferrofluids are liquids that react to magnetic fields without solidifying. They consist of a few nanometer-sized magnetic particles, which are suspended in colloidal suspension in a carrier liquid. The particles are generally stabilized with a polymeric surface coating.

Genuine ferrofluid is stable dispersion, which means that the solid particles do not settle with time and do not accumulate in extremely strong magnetic fields or separate from the liquid as another phase.

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