An object or material that has a magnetic field is called a magnet. There are several variations, for example, it is an electromagnet. A magnetic field is created due to the strength of the current that flows through the copper coils and creates a magnetic induction or magnetic field at the ends of the core. Without power supply, such a magnet will not work and the magnetic field will disappear. A permanent magnet has its own magnetic field without consuming extraneous energy in the form of electricity; a magnet is made of ferromagnetic materials that retain the residual magnetization for a long period of time.

Permanent magnets are made from different ferromagnets. The simplest and most common magnets are ferrite magnets, they are black in color and have a low cost. A new generation of permanent magnets appeared by the end of the 20th century. Rare-earth supermagnets in their composition rare-earth elements such as Nd-neodymium, Sm-samarium, Co-cobalt and others are used. In spite of their high cost, such magnets are widely spread due to their properties. For example a permanent magnet based on neodymium ( Neodymium magnet ) has induction or magnetic force 10 times more than a ferrite magnet and resistance to demagnetization ~ 2% for 10 years, this means that in 100 years of using a magnet, it will lose only 20% of its strength !!! The most popular rare-earth magnets are neodymium, the production technology is complex. They are made by sintering NdFeB alloy in a vacuum furnace at a temperature of 1200 degrees and are coated with a silver-colored anti-corrosion coating (Ni-Cu-Ni). The resulting magnets can have a magnetic induction of up to 330 kJ / m. The strength of neodymium magnets exceeds its own weight a hundred times, for example, a neodymium magnet weighing 1 kg can have a peel strength of 150 kg. The same magnet from ferrite will be 10 times weaker. Neodymium magnets due to their small size, high magnetic force and resistance to demagnetization began to be used in military and high technology in various industries such as computer equipment, medicine, precision instruments, wind generators, mobile phones, separators, acoustics and others - this is far from complete list of permanent magnets.

You can get acquainted with neodymium magnets on the site http://megamag.in.ua