Magnetic Fields
The area that surrounds a magnet that exerts force is called the magnetic field. A magnetic field is caused by the motion of electric charge. Each electric charge is in constant motion around the nuclei. The motion creates a small current, which creates the magnetic field. Atoms contain different amounts of electrons, which is why some atoms are more magnetic than others. If two electrons are spinning in the same direction, the magnetic field is stronger. This happens in elements like Iron. If a pair of electrons are spinning in opposite directions, the charge is cancelled out and creates no magnetic field. This is what happens in plastics and wood.
The shape of the field is determined by the magnetic filed lines. The lines start at the north pole and end at the south pole. The poles lie at each end of the magnet and are the strongest part of the magnet because this is the area where the magnetic field lines are the close together.
Magnetic Domains
Because magnetic fields are strong, groups of atoms surrounding the magnet will begin to shift and align themselves with the field lines. These aligned groups are called Magnetic Domains. This is the difference between a magnetized and unmagnetized object. An object, like iron, that has randomly oriented domains is not magnetic. But, if the domains are aligned in the way of the field lines, it is magnetic. The more aligned the domains, the stronger the magnet. When a magnet attracts a metal, the domains of the metal align to the field lines of the magnet, but when pulled away, the domains return to a random state. With some materials, the domain stays aligned which creates a temporary magnet.
The Earth's Magnetic Field
The Earth acts as a giant magnet although it is still not clear as to why. The North pole of a magnetic is attracted to the North Pole of the Earth, and the south pole is attracted to the South Pole of the Earth. Although, these magnetic poles are not the same as the geographical North and South poles of the Earth. Another misconception about the North and South poles is that the North Pole is actually a South pole in terms of magnetism, because North Poles are attracted to South Poles, and vice versa.
