An iron ring is not inherently magnetic in its natural state, but it can become magnetic under certain conditions.
Magnetization of Iron
Iron is a ferromagnetic material. This means that its atoms have magnetic moments that can align with each other. However, in a typical iron ring, these magnetic moments are randomly oriented, resulting in a net magnetic field of zero. Therefore, the iron ring doesn't act as a magnet.
Becoming Magnetic: Induction
An iron ring can become magnetized when exposed to an external magnetic field. This process is called magnetic induction. When placed within a magnetic field, the magnetic domains within the iron align with the external field, causing the iron to become magnetized. The strength of the induced magnetic field depends on the strength of the external field and the properties of the iron. Soft iron, in particular, is easily magnetized and demagnetized.
Consider the reference provided: "The soft-iron ring enhances the strength of the magnetic field, and the ring itself becomes magnetized." This describes a scenario where the iron ring is used to increase the magnetic flux and, in doing so, becomes temporarily magnetized itself. When the external magnetic field is removed, the soft iron ring will lose most of its magnetism.
Permanent Magnets vs. Temporary Magnets
It's crucial to distinguish between permanent and temporary magnets. An iron ring is usually a temporary magnet. It only exhibits magnetic properties when an external magnetic field is present. Once the external field is removed, the iron loses its magnetism (especially if it's soft iron). Materials like Alnico or rare-earth magnets can be made into permanent magnets which retain their magnetism even without an external field.
Examples
- Electromagnets: Iron cores are often used in electromagnets. When a current is passed through a coil of wire wrapped around an iron core, the iron core becomes strongly magnetized, enhancing the magnetic field produced by the coil.
- Transformers: As highlighted in the reference, iron rings (or cores) are used in transformers to increase the efficiency of energy transfer between coils.
