A magnet is an object that generates a magnetic field. This field produces a force that can pull certain materials towards it or push other magnets away. While the concept of attraction to a magnet may seem straightforward, not all materials interact with magnetic fields in the same way. The degree to which a material is affected depends on its internal atomic structure and how its electrons behave.
Strongly Attracted Materials
Materials exhibiting a strong attraction to magnets are known as ferromagnetic materials. This category includes elements like iron, nickel, and cobalt. These elements can be strongly magnetized and retain their magnetism even after an external magnetic field is removed. For instance, iron is a component in many magnetic items, including refrigerator magnets and tools.
Beyond pure elements, several alloys also display strong magnetic properties. Steel, an alloy of iron and carbon, is strongly magnetic. Another example is alnico, an alloy of aluminum, nickel, cobalt, and iron. These materials are often used to create permanent magnets because they produce strong, stable magnetic fields.
Weakly Attracted and Repelled Materials
While ferromagnetic materials are strongly attracted to magnets, other substances exhibit different interactions with magnetic fields. Paramagnetic materials are weakly attracted to strong magnetic fields. However, they do not retain magnetic properties once the external field is removed. Examples of paramagnetic materials include aluminum, platinum, and oxygen. When placed in a magnetic field, these materials show a slight alignment with the field’s direction.
In contrast, diamagnetic materials are weakly repelled by magnetic fields. This means they move away from stronger magnetic fields. Common examples are water, copper, gold, and bismuth. Unlike ferromagnetic or paramagnetic materials, they do not possess permanent magnetic moments, and their magnetic susceptibility is negative. Their repulsion is very subtle and requires sensitive instruments to detect.
The Science Behind Magnetic Attraction
The origin of magnetism lies within the atomic structure of materials, with electrons. Electrons, which constantly move within atoms, possess an intrinsic property called “spin” that generates tiny magnetic fields. This spin creates a magnetic moment, essentially making each electron behave like a miniature magnet. In most materials, these individual electron magnetic moments are randomly oriented or paired so their fields cancel out, resulting in no net magnetism.
However, in ferromagnetic materials, an atomic arrangement allows these magnetic moments to align within regions called magnetic domains. Within each domain, the magnetic fields of atoms point in the same direction, creating a strong localized magnetic force. When an external magnetic field is applied, these domains can reorient themselves, causing their individual magnetic moments to align with the external field. This collective alignment results in the strong magnetic attraction characteristic of materials like iron, nickel, and cobalt. The absence of such aligned domains or paired electrons explains why other materials are not strongly attracted or are even repelled by magnets.