Magnets get their power of attraction from their atomic structure. One important part of a magnet's atomic structure is its domains. However, materials that are not magnetic also possess domains. One example of a nonmagnetic material that possesses domains and can be made into a magnet is an iron nail. By understanding how to make an iron nail magnetic you will learn what the domains are in a magnet.
Magnet Atomic Theory
Atoms consist of protons, neutrons and electrons. The inner region of an atom is its nucleus, made up of protons and neutrons. The outer region is made up of spinning electrons that orbit the nucleus. The spinning of the electrons creates magnetic fields called dipoles that are like tiny bar magnets. When the majority of the electrons spin in the same direction, they give an atom its magnetic field. Iron is an example of a material with atoms that have a magnetic field. Aluminum is an example of a material whose atoms do not have a magnetic field.
Magnetic Molecular Structure
When a material possesses atoms with magnetic fields, the material has the potential to become a magnet. However, the atoms' molecular structures must be aligned relative to each other. If the atoms in the material are oriented randomly they will cancel out each other's magnetic field. Iron is an example of a material consisting of atoms with magnetic fields that are aligned with each other.
Materials consisting of atoms with magnetic fields that are aligned with each other will cluster into groups called domains. These domains produce a stronger magnetic field than any single atom. Domains must be aligned relative to each other to make a material magnetic. A typical iron nail consists of atoms with magnetic fields that are aligned. However, to make the nail magnetic, its domains must be aligned as well. The alignment of multiple domains creates a stronger attractive force than that of a single domain.
Making a Magnet
Making a magnet out of a nail is a simple process requiring a method that forces the magnetic domains within the nail to orient in the same direction. One method is to hold a permanent magnet in one hand and stroke the nail several times in the same direction from end to end. The magnetic field of the permanent magnet forces the magnetic domains within the nail to align with the field lines of the permanent magnet.
A second method is to position the nail in a magnetic north-south orientation while striking the nail sharply with a hammer several times. The blunt force of the hammer causes the domains to break apart from each other. At the same time, the earth's magnetic field forces the nail's domains to reorient along the earth's magnetic field lines.
With either method the nail becomes a magnet due to its magnetic domains aligning into a complementary orientation that combines the strength of their magnetic fields.