Know the "permanent magnet"

In the absence of an external magnetic field, it can maintain its own magnetic objects for a long time. Permanent magnets can be made of ferromagnetic materials such as iron, nickel, and the like.

Its atomic structure is special, and the atom itself has a magnetic moment. The general arrangement of these minerals is disordered, and the magnetic domains do not show magnetic interaction. However, when the external forces, such as magnetic fields, guide the alignment of the molecules, magnetic properties appear. This is commonly known as magnets. Iron, cobalt, and nickel are the most commonly used. Magnetic material. Basically, the magnets are divided into permanent magnets and soft magnets. The permanent magnets are coupled with strong magnets to align the spin and electron angular momentum of the magnetic material in a fixed direction; soft magnetism is to add current, etc. The current is removed and the soft iron will slowly lose. magnetic. A magnet is just a generic term, it is generally referred to as having magnetic properties, and the actual composition does not necessarily contain iron. The purer metallic iron itself has no permanent magnetism, and only near permanent magnets will induce magnetism. General permanent magnets add other impurity elements such as carbon to stabilize the magnetism, but this will reduce the freedom of electrons. It is not easy to conduct electricity, so when the current passes through, the light bulb will not light up. Iron is a common magnetic element, but many other elements have stronger magnetic properties. Many powerful magnets are made of a mixture of bismuth, iron, and boron.

Magnetic resistance: A measure of the permanent magnetic properties of a permanent magnetic material against magnetic and non-magnetic interferences.