where do magnets come from
Answers to where do magnets come from
Magnets can be made by placing a magnetic material such as iron or steel, in a strong magnetic field. Permanent, temporary and electromagnets can be made in this manner.
The atoms forming materials that can be easily magnetized such as iron, steel, nickel, and cobalt are arranged in small units, called domains. Each domain, although microscopic in size, contains millions of billions of atoms and each domain acts like a small magnet. If a magnetic material is placed in a strong magnetic field, the individual domains, which normally point in all directions, gradually swing around into the direction of the field. They also take over neighbouring domains. When most of the domains are aligned in the field, the material becomes a magnet.
Electromagnets are used when really strong magnets are required. Electromagnets are produced by placing a metal core (usually an iron alloy) inside a coil of wire carrying an electric current. The electricity in the coil produces a magnetic field. Its strength depends on the strength of the electric current and the number of coils of wire. Its polarity depends on the direction of the current flow. While the current flows, the core behaves like a magnet, but as soon as the current stops, the magnetic properties are lost. Electric motors, televisions, maglev trains, telephones, computers and many other modern devices use electromagnets.
What are superconductors?
These are the strongest magnets. They don't need a metal core at all, but are made of coils of wire made from special metal alloys which become superconductors when cooled to very low temperatures.
There are many legends accounting for the discovery of magnets. One of the most common, is that of an elderly shepherd named Magnes, who was herding his sheep in an area of Northern Greece called Magnesia, about 4,000 years ago. It is said that both the nails in his shoes and the metal tip of his staff became firmly stuck to the large, black rock on which he was standing. This type of rock was subsequently named magnetite, after either Magnesia or Magnes himself.
Stories of magnetism date back to the first century B.C in the writings of Lucretius, and the magical powers of magnetite are mentioned in the writings of Pliny the Elder. For many years following its discovery, magnetite was surrounded in superstition and was considered to possess magical powers, such as the ability to heal the sick, frighten away evil spirits and attract and dissolve ships made of iron! Unlike amber (fossilized tree resin), magnetite was able to attract objects without first being rubbed. This made magnetite far more magical. People soon realized that magnetite not only attracted objects made of iron, but when made into the shape of a needle and floated on water, magnetite always pointed in a north-south direction creating a primitive compass. This led to an alternative name for magnetite, that of lodestone or "leading stone".
Who discovered magnets?
The first attempt to separate fact from superstition came in 1269, when a soldier named Peter Peregrinus wrote a letter describing everything that was known, at that time, about magnetite. It is said that he did this while standing guard outside the walls of Lucera which was under siege. While people were starving to death inside the walls, Peter Peregrinus was outside writing one of the first 'scientific' reports and one that was to have a vast impact on the world. It wasn't until the experiments of William Gilbert in 1600 that significant progress was made in the understanding of magnetism and it was another century or so before other scientists began, by experimentation, to understand the phenomenon.
Who were the scientists who helped us to understand magnets?
It was William Gilbert who first realized that the Earth was a giant magnet and that magnets could be made by beating wrought iron. He also discovered that the induced magnetism was lost if the iron was heated. In 1820, Hans Christian Řersted, demonstrated for the first time (at a public lecture), that there was a relationship between electricity and magnetism.
What is magnetite?
Magnetite is found in rock strata associated with iron deposits and has been found in the ocean floor dating from 2 to 55 million years old. Magnetite is magnetic because its molecular structure has allowed it to retain the alignment of particles caused by the Earth's magnetic field during its formation millions of years ago. When heated to high temperatures magnetite loses its natural magnetism. Not all iron deposits are magnetic, however, which for many years posed a question. Why is magnetite only formed in certain iron deposits? Recently an interesting theory has emerged concerning an anaerobic bacterium, GS-15, which has been shown to convert ferric oxide into magnetite. It is thought that GS-15, could be responsible for the creation of magnetite layers in many iron formations.
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