Chinese name: 磁铁 Force typically produce: Attraction, repulsion English name: magnet Applied science: Physics
Main ingredient: Iron, cobalt, nickel, etc. Areas of: electromagnetism Magnet
A magnet capable of generating a magnetic field, a ferromagnetic substance having interesting such as iron, nickel, cobalt and other metal features.
The midpoint of the bar magnet suspended by a thin line, when stationary, its ends will each point to the Global South and the North, called the finger pointing towards the north end of the North Pole or N-pole, pointing to the south end of the guide pole or S pole.
If the thought of a big magnet Earth, the Earth's magnetic north pole is a guide, it refers to the geomagnetic North Pole South Pole. Between the magnet and the magnet, repelling poles of the same name, synonym of magnetic pole attracting. So, compass and Antarctic repulsion, compass and Arctic repulsion, and the compass and compass with attractive.
Category: magnets can be divided into "permanent magnet" and "non-permanent magnets." The permanent magnet may be a natural product, also known as natural magnet to be manufactured by the human user. Non-permanent magnets, such as magnet, only under certain conditions to appear magnetic.
Discovery Magnets are not invented by human, it is a natural magnetite. The ancient Greeks and Chinese people find nature a kind of natural magnetization of stone, called "magnet." This stone can magically pick up small pieces of iron sheets, and free to swing always point in the same direction. Early sailors call this magnet as the first to identify the direction of the compass at sea. The earliest discovery and use magnets should be Chinese people, that is, "compass", is one of the four great inventions of China.
Over thousands of years of development, today has become a magnet strong material in our lives. By alloy synthesis of different materials to achieve the same effect with a magnet, but also can improve the magnetic force. In the 18th century there have been man-made magnets, but the manufacturing process of a stronger magnetic material is very slowly until the 1920s to produce aluminum-nickel-cobalt (Alnico). Subsequently, the 1950s produced the ferrite (Ferrite), 70 years to produce rare earth magnets [Rare Earth magnet including neodymium iron boron (NdFeB) and samarium cobalt (SmCo)]. Thus, magnetic Technology has been developing rapidly, so that the element of magnetic materials are also more compact.
Development In 1822, French physicist Arago and Lussac found that when the current through the winding including iron, which enables winding of iron magnetized. This is actually the initial discovery of the principle of the electromagnet. In 1823, Sturgeon also did a similar experiment: He is not on a U-shaped iron bar magnet rod 18 laps around the bare copper, copper wire and a voltaic battery when turned around in the U copper coil type iron bar on the magnetic field that is generated intensive, thus making a U-shaped piece of iron rod into a "solenoid." Magnetic energy than on the permanent electromagnet can zoom times, it can pick up more than 20 times its weight of iron, and when the power is turned off, U type iron bar on what iron could not suck again become a Root ordinary iron bar. Sturgeon electromagnet invention, so that people see the electrical energy into magnetic energy of a bright future, this invention quickly spread in the United Kingdom, the United States and Western Europe, some coastal countries. In 1829, American scientist Henry Sturgeon electric solenoid means a number of innovations, wires instead of bare copper wire, copper wire and therefore do not have to worry about being too close to a short-circuit. Since the wire with insulation, they can be wound together tightly around the enclosure, since more intensive coil, the stronger the magnetic field generation, thus greatly improving the ability to convert electrical energy into magnetic energy. 1831, Henry trial out of a newer electromagnet, although its volume is not large, but it can pick up the one-ton iron. Electromagnet invention also enables the generator power has been greatly improved.
Development path 5,000 years ago, humans discovered natural magnet (Fe3O4)
2300 years ago, Chinese people will naturally magnet dippers on a smooth ground plane under the influence of geomagnetism, spoon handle guide, said, "Ian," namely, the world's first guide instrument.
1000 years ago, Chinese people friction magnetized needle with a magnet and iron, made the world's first compass.
China around 1100 and orientation of the magnet needle plate into one, becoming magnet guide instrument used for navigation.
1405-1432 Zheng guide instrument began with the history of mankind sailing great initiative.
1488-1521 Columbus, Gama, Magellan came directory with the Chinese instruments were world famous voyages of discovery.
1600 Englishman William Gilbert published a monograph on magnetic "Magnet" repeated and developed the knowledge and previous experiments related to magnetism.
1785 French physicist C. Coulomb chessboard with a twist established between the description of the charge and magnetic forces "Coulomb's law."
1820 Danish physicist HC Oersted found that the current induced magnetic force.
1831 British physicist M. Faraday discovered electromagnetic induction.
1873 British physicist JC Maxwell completed the unification of electromagnetic theory in his monograph "On the electric and magnetic" in.
1898-1899 French physicist P. Curie ferromagnetic substance found in certain temperature (Curie temperature) becomes paramagnetic phenomenon.
1905 French physicist Langevin PI based on statistical mechanics to explain the paramagnetic temperature changes.
1907 French physicist PE outer Christie the molecular field theory, expanding the Langevin theory.
1921 Austrian physicist W. Pauli asked Bohr magneton as the basic unit of atomic magnetic moments. American physicist A. Compton electrons have spin propose appropriate moments.
1928 British physicist PAM Dirac's relativistic quantum mechanics perfectly explains the intrinsic spin and magnetic moment of the electron. And together with the German physicist W. Heisenberg proved the existence of exchange forces of electrostatic origin, laid the foundation of modern magnetism.
1936 Soviet physicist Landau completed the monumental work "theoretical physics course", which contains a comprehensive and brilliant exposition of modern electromagnetic and ferromagnetic school chapter.
1936-1948 French physicist L. Neel put forward the concept and theory of antiferromagnetic and ferrimagnetic, and in the subsequent years of study to deepen the understanding of the magnetic material.
Austrian-American physicist KJ SINATE 1967 under the guidance of quantum magnetism found unprecedented high energy product rare earth magnets (SmCo5), which opened a new chapter in the development of permanent magnet material.
In 1967, Strnat Dayton and other US universities, developed into a samarium cobalt magnets, marking the arrival of the era of rare earth magnets.
1974 came the second generation of rare earth permanent magnet -Sm2Co17.
1982 Sumitomo Special Metals Sagawa reality (Masato Sagawa) invention of NdFeB magnet, the third generation of rare earth permanent magnet -Nd2Fe14B available.
1990 atomic gap between the magnet -Sm-Fe-N come out.
1991 German physicist EF Kenei Le presented the theoretical basis of the two-phase composite magnetic exchange interaction, pointing out the prospect of nanocrystalline magnet.
With the development of society, the application of the magnets are increasingly being used, from high-tech products to the most simple packaging magnetic,
Currently the most widely used or NdFeB magnets and ferrite magnets.
From the history of the magnet, the turn of the century, people mainly use carbon steel, tungsten steel, chrome steel and cobalt permanent magnet material for steel.
Thirties
The late 1930s, the successful development of aluminum-nickel-cobalt magnet, the magnet that makes large-scale applications possible.
Fifties
Fifties, there barium ferrite magnet, not only reduces the cost of a permanent magnet, in turn broaden the scope of application of permanent magnet materials to high-frequency fields.
Sixties
The sixties, samarium cobalt permanent magnet occurred, on the application of the magnet has opened up a new era. So far, the rare earth permanent magnet has experienced first-generation SmCo5, the second generation of precipitation hardened Sm2Co17, developed to the third generation of Nd-Fe-B permanent magnet materials. Ferrite magnets are still present, the largest amount of permanent magnet materials, NdFeB magnets value but has greatly exceeded the ferrite permanent magnet materials, NdFeB magnet production has become a major industry.
