Magnetization refers to the phenomenon that under the action of a magnetic field, the orientation of the magnetic moments in the material tends to be uniform when the magnetic moments are arranged, which shows a certain degree of magnetism.
The process of obtaining magnetism from a substance that does not originally have magnetism. Some objects will show magnetism under the action of magnets or electric current. This phenomenon is called magnetization.
Ferromagnetic materials can be magnetized in the following ways:
1. Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal.
2. Placing the item in a solenoid with a direct current passing through it.
When magnetizing objects, the results will be considered to be "soft" or "hard":
1. A "soft" or "impermanent" magnet is one that loses its memory of previous magnetizations. "Soft" magnetic materials are often used in electromagnets to enhance (often hundreds or thousands of times) the magnetic field of a wire that carries an electrical current and is wrapped around the magnet; the field of the "soft" magnet increases with the current.
2. A "hard" or "permanent" magnet is one that stays magnetized for a long time, such as magnets often used in refrigerator doors and magnetic jewellery. Permanent magnets occur naturally in some rocks, particularly lodestone, but are now more commonly manufactured.
A magnet's magnetism decreases when it is heated and increases when it is cooled.
