The ancient Greeks and Chinese discovered a kind of naturally magnetized stone in nature and called it "magnetite". This kind of stone can magically suck up small pieces of iron, and it always points in the same direction after swinging at will. Early navigators used this magnet as their earliest compass to identify directions at sea. After thousands of years of development, magnets have become powerful materials in our lives today. By synthesizing alloys of different materials, the same effect as the magnetite can be achieved, and the magnetic force can be improved. Artificial magnets appeared in the 18th century, but the process of making stronger magnetic materials was very slow, until Alnico was made in the 1920s. Subsequently, ferrite was manufactured in the 1950s, and rare earth magnets were manufactured in the 1970s Rare Earth magnet includes neodymium iron boron (NdFeB) and samarium cobalt (SmCo). So far, magnetic technology has developed rapidly, and strong magnetic materials have also made the components more compact.
What is the magnetization (orientation) direction?
Most magnetic materials can be magnetized to saturation in the same direction. This direction is called the "magnetization direction" (orientation direction). Magnets without orientation direction (also called isotropic magnets) are much weaker than oriented magnets (also called anisotropic magnets).
What is the standard "Antarctic" industrial definition?
The definition of "north pole" is that the north pole of the magnet points to the north pole of the earth after it rotates at will. Similarly, the south pole of the magnet points to the south pole of the earth. How to identify the north pole of a magnet without marking?
Obviously, it is impossible to tell by eyes alone. You can use the compass to get close to the magnet, and the pointer to the north pole of the earth will point to the south pole of the magnet.
How to handle and store magnets safely?
Always be very careful, because the magnets will stick together by themselves, which may pinch your fingers. When the magnets are attracted to each other, the magnet itself may be damaged due to collision (knock off the corners or cracks). Keep magnets away from items that are easily magnetized, such as floppy disks, credit cards, computer monitors, watches, mobile phones, medical equipment, etc. The magnet should be far away from the pacemaker.
For larger size magnets, plastic or hard paper spacers should be added between each piece to ensure that the magnets can be easily separated. Magnets should be stored in a dry, constant temperature environment as much as possible.
How to achieve magnetic isolation?
Only the material that can be adsorbed to the magnet can cut off the magnetic field, and the thicker the material, the better the magnetic shielding effect. What is the strongest magnet?
The current highest performance magnets are rare earth magnets. Among the rare earth magnets, neodymium iron boron is the most powerful magnet. But in an environment above 200 degrees Celsius, samarium cobalt is the strongest magnet.
