Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomenon in other entities.
12.2.A.1 Magnetic dipoles result from electric charge moving in a circle. In magnetic materials this can be the motion of electrons.
Permanent magnetism or induced magnetism of matter is a system property resulting from the alignment of magnetic dipoles within the system.
No magnetic north pole is ever found in isolation from a south pole. For example, if a bar magnet is broken in half, both halves are magnetic dipoles in themselves.
Magnetic poles of the same polarity will repel; magnetic poles of opposite polarity will attract.
12.2.A.2 A magnetic dipole placed in a magnetic field will tend to align with the magnetic field. 12.2.A.3 A material’s composition influences its magnetic behavior in the presence of an external magnetic field.
Ferromagnetic materials such as iron, nickel, and cobalt can be permanently magnetized by an external field that causes the alignment of magnetic domains or atomic magnetic dipoles.
Paramagnetic materials such as aluminum, titanium, and magnesium interact weakly with an external magnetic field, in that the magnetic dipoles of the material do not remain aligned after the external field is removed.
12.2.A.4 Earth’s magnetic field may be approximated as a magnetic dipole.
Dr Meghan Gray chats about magnetic fields and the Earth's changeable poles.
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