to understand this text.
mind. We’ll tell you. All electronic and electric equipment has some
magnetic field inside it. A
saves files on a magnetic disk called “HD”
(Hard Drive). The power
source of any electronic machine only works thanks to magnetic fields. Without magnetism we wouldn
Without magnetism we wouldn’t have cars, planes, household appliances, radio, television, computers, medical machines, we wouldn’t have anything.
BC - Lodestone
magnetic properties of natural ferric ferrite (Fe3O4)
stones (lodestones) were described by Greek philosophers.
- First Reference to a Compass
Neckem an English monk of
- First Detailed Description of a Compass
Peregrinus de Marincourt, a French Crusader, describes a floating
compass and a compass with a pivot point.
- Electromagnetism, Current
- Electromagnetic Induction
Faraday (1791-1867) an Englishman, made one of the most significant
discoveries in the history of electricity: Electromagnetic induction.
His pioneering work dealt with how electric currents work. Many inventions
would come from his experiments, but they would come fifty to one
hundred years later. His brilliant mind took earlier experiments still
further. If electricity could produce magnetism, why couldn't magnetism
produce electricity? In 1831, Faraday found the solution. Electricity
could be produced through magnetism by motion. He discovered that
when a magnet was moved inside a coil of copper wire, a tiny electric
current flows through the wire. These experiments, convincingly demonstrated
the discovery of electromagnetic induction in the production of electric
current, by a change in magnetic intensity.
- DC Motor
Oersted developed the discoveries of Faraday till the point of making
the first DC motor.
- DC Generator
his motor and generator, making it possible commercial use of the
generator. By 1872, Siemens and Halske of Berlin improved on Gramme's
generator, by producing the drum armature. Other improvements were
made, such as the slotted armature in 1880 but by 1882,
- Cobalt Steel Magnets
Honda and T. Takai add cobalt to tungsten steel to increase the coercive
force of permanent magnets improving industrial applications.
- Commercial Steel Magnets
first commercially available quench-hardened steel magnets were made
- Alnico Magnets
produces the first Alnico magnet containing an alloy of iron, nickel,
and aluminium. Alnico magnets are widely used in loudspeakers and
headphones among many other applications, till today.
- Rare-Earth Magnets
Karl J. Sternat at the U.S. Air Force Materials Laboratory at Wright-Patterson
Air Force Base discovers the high-energy product (18 MGOe) of the
Samarium-Cobalt (SmCo5) compound.
- Advanced Rare-Earth Magnets
Karl J. Sternat and Dr. Alden Ray develop a higher energy product
(30 MGOe) Samarium-Cobalt (Sm2Co17) compound.
- Neodymium-Iron-Boron Magnets
Motors, Sumitomo Special Metals and the
Lee, E. W.: Magnetism, An Introductory Survey, Dover Publications Inc. (1970)
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