magnetize

Magnetize is the process by which a material or object is given magnetic properties or an enhanced magnetic response. In general, magnetization is the alignment of atomic or molecular magnetic moments within a material, producing a net magnetic dipole moment. An external magnetic field can induce this alignment, and some materials retain it to varying degrees after the field is removed, depending on their magnetic characteristics.

Most common magnets are made from ferromagnetic materials such as iron, nickel, cobalt, and their alloys. Soft magnetic materials are easily magnetized and demagnetized; hard magnetic materials retain magnetization longer. Methods to magnetize include applying a strong external magnetic field, stroking or rubbing a piece with a magnet, and winding a coil around the material and passing current through it (electromagnetization). The relationship between the magnetic field H, flux density B, and magnetization M is described by B = μ0(H + M) in SI units.

Key properties include remanent magnetization (remanence) and coercivity, which determine how long a material stays magnetized and how resistant it is to demagnetization. Temperature also affects magnetization; above the Curie temperature, ferromagnetism is lost. Magnetization is central to many applications, including permanent magnets for motors and generators, magnetic storage, transformers, loudspeakers, and sensors.

Safety and handling concerns arise with strong magnets, which can cause injury or interfere with electronic devices and medical implants. Proper precautions are advised when using or transporting high-strength magnets.