ID 30
Magnetic Term Magnetic Domains
Video Magnetic Domains

We know magnets aren’t attracted to everything; if we put a magnet on a wooden wall, it will fall right down. Generally, magnets are attracted to objects that are made of the metals iron, nickel, or cobalt. These materials are called ferromagnetic materials. The reason magnets stick to these metals is because of a special characteristic about the atoms inside these metals. In most other materials that are not magnetic, the magnetic moments of the atoms inside are all oriented in random directions that cancel each other out. In ferromagnetic materials, the atoms form structures called domains. A domain is a region inside of a material where groups of magnetic moments naturally align in the same direction.

Domainsmagnetic domain drawing

There can be numerous domains within an object. When there is no external magnetic field present, the domains are also oriented randomly so that there is no net magnetic field. However, when an external magnetic field is present, the domains will rotate and align with the external magnetic field. When all or most of the domains are aligned in the same direction, the whole object becomes magnetized in that direction and becomes a magnet.

domains  magnetic domains

The process of using a magnetic field to magnetize another object is called induction. Once a magnet has been induced, it produces its own magnetic field as long as its domains are aligned.

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