Magnetism is a force that is created when objects are attracted or repelled by one another. A magnetic field is the area around a magnet. The larger the magnet and the closer an object is to the magnet, the greater the force of the magnetic field.
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Every magnet, whether large or small, has exactly two poles. At these poles is where the magnetic strength of the magnets is the strongest. Each pole is either north or north-seeking or south or south-seeking. Like objects (such as two north poles of two magnets) repel each other. Unlike objects (such as a north pole of one magnet and a south pole of another magnet) attract each other.
The particular attraction or repulsion of two magnets depends on the strength of their magnetic fields. In particular, the bigger the distance that separates the magnets, the weaker their magnetic force and the smaller the distance that separates the magnets, the stronger their magnetic force. Another important feature of magnets is that when a magnet is shattered or broken into pieces, a new north and south pole will appear on the smaller pieces.
Magnetic properties of lodestones (natural ferric ferrite stones) were discovered in 600 BC by Greek philosopheres. During the same time, Aristophanes became aware of the mineral amber's special property of attracting particular materials, such as feathers. The reasons behind this attraction remained a mystery until Dr. William Gilbert examined amber and magnets more fully in 1600. Dr. Gilbert was a court doctor for Queen Elizabeth the First and is credited with discovering that other substances besides amber have electrical and attraction powers. He noted that a force was created and transferred and referred to this as an electric charge. Gilbert also wrote a paper called "De Magnete" which was the first work that explained the compass needle's ability to point north and south. "De Magnete" stated that the Earth itself is magnetic and paved the way for the future achievements of Newton, Kepler, Galileo, among others.
There are a few laws that govern the behavior of magnets. All magnetic poles are equal in magnitude (strength) and if a magnet is broken into smaller magnets, each section becomes its own magnet with two poles of equal strength. Short bar magnets (such as U-shaped magnets and horseshoe magnets) do not retain magnetism as well as long bar magnets.
Magnets that are hammered, twisted, or heated do not magnetize as well as magnets that were not subjected to these actions. This happens because those actions partially break and, as a result, impair the linear arrangement of the magnet's molecules. However, demagnetization can also be reversed.