magnetising

Magnetisation is the process by which a material becomes a magnet. This can occur naturally or through artificial means. Natural magnetisation happens when a ferromagnetic material, such as iron ore, is exposed to a strong magnetic field for a prolonged period, often due to the Earth's magnetic field.

Artificial magnetisation typically involves exposing a ferromagnetic material to a stronger external magnetic field. This can be achieved by placing the material inside a solenoid with an electric current flowing through it, or by rubbing it in one direction with a permanent magnet. The magnetic field causes the magnetic domains within the material, which are tiny regions with aligned atomic magnetic moments, to align themselves in the direction of the external field.

The degree of magnetisation depends on the material's properties and the strength and duration of the applied magnetic field. Materials like iron are easily magnetised and demagnetised, making them suitable for electromagnets, while materials like steel retain their magnetism once the external field is removed, making them useful for permanent magnets. The process of magnetisation is reversible; a magnetised material can be demagnetised by heating it above its Curie temperature or by exposing it to an opposing magnetic field.