Physics: How Objects Borrow Their Magnetism

Magnetism is not simply a property that objects either have or lack — it is a behaviour that depends on the material and how it responds to nearby magnetic fields. When a paperclip or iron nail touches a bar magnet, it becomes magnetically induced, temporarily aligning its domains and attracting other magnetic materials. This phenomenon, known as magnetic induction, explains why unmagnetised objects can behave like magnets while in contact with a stronger magnetic source. The key distinction lies in retentivity — a material's ability to retain magnetism after the external field is removed. Soft magnetic materials, such as iron, lose their magnetism quickly once the inducing magnet is taken away, making them temporary magnets. Hard magnetic materials, like steel, retain their magnetism and become permanent magnets. Understanding this difference matters because it underpins how electromagnets, transformers, and data storage devices are designed, connecting material properties directly to real-world applications.