Basics of Magnets
What is a magnet?
Magnets are objects made with specific elements, creating a magnetic field. All magnets have at least two poles – north and south – with the magnetic field lines exiting the north end and re-entering at the south end of the magnet.
Every magnet retains a north and south pole, regardless of size, even if it has been broken into multiple pieces. Researchers have yet to discover a monopole magnet – a magnet with just one pole.
How do magnets work?
Much of the science of magnets is a mystery. However, scientists have discovered the science behind magnetic force. It starts with matter – physical substances which make up all objects in the universe – and the microscopic atoms which make up matter.
Each atom has a nucleus, composed of protons and neutrons. Circling the nucleus are electrons, which generally orbit in pairs. This movement creates a tiny magnetic field. When multiple pairs of electrons move about the nucleus in opposite directions, their magnetic fields cancel one another out. When an atom – such as iron – has an odd number of electrons, those unpaired electrons create a magnetic field, turning the entire atom into a tiny magnet.
When a majority of the atoms in an object are tiny magnets, it produces an overall magnetic field with a north and south pole.
The History of Magnets
Records show references to magnetic properties as early as 600 B.C. The Greeks first used the word “magnet” to describe a stone that attracted iron and other ferrous pieces to itself. Additional origins of the word are credited to a shepherd named Magnes who discovered the stone while tending to his flock, as well as the ancient city of Magnesia (now Manisa in modern-day Turkey) where many magnetic stones were found.
Compasses used by mariners were among early, important magnetic devices. It was discovered that a magnet, when allowed free movement, always pointed in the same north-south direction. Previously, mariners had struggled to navigate when skies were clouded, blocking the guidance from the sun and stars.
Magnets in Everyday Use
Magnets have many applications in everyday life. From magnetic clips and push pins – good for use in the kitchen, classroom or office – to heavy duty retrieving, separating and welding magnets designed for use in manufacturing shops. Magnets have a variety of applications.
Types of Magnet Material
There are five types of magnet material:
Alnico magnets are made primarily from (Al), (Ni) and (Co), hence al-ni-co. Alnico magnets are available in a variety of shapes and sizes and are very temperature stable. They produce a strong magnetic field and are commonly known for their popularity as red horseshoe or bar magnets.
Composed of strontium carbonate and iron oxide, ceramic (ferrite) magnets are one of the popular types of magnet, partly due to their cost-efficiency. They can be manufactured in the forms of discs, rings, blocks, cylinders and sometimes arcs. Ceramic magnets have a variety of applications, including speakers, Magnetic Resonance Imaging (MRI) and magnetic assemblies of holding, retrieving and separating.
High Energy Flexible
Made from a strontium ferrite powder mixture with polymer bonding, these magnets most commonly are used in strips. The magnets are anisotropic (oriented) and have high-resistance to weather and natural elements, making them ideal for both indoor and outdoor usage. High Energy Flexible magnets can be manufactured with adhesive for permanent application or plain and are inexpensive compared to other forms of magnetic material.
Neodymium magnets (NdFeb, NIB, Neo), also known as “rare earth magnets,” are composed of neodymium, iron, boron and transition metals. Despite their small size, these magnets are incredibly powerful and are the strongest magnetic material available. Neodymium magnets should be handled with care to avoid injury and can be used in a variety of environments and magnetic assemblies.
A second type of rare earth magnet, it is composed of samarium, cobalt and iron. Samarium Cobalt (SmCo) magnets have high resistance to demagnetization, good temperature stability and are the second strongest permament magnets available.