There are many types of magnets. Let’s look at them in some detail.
Natural magnets or loadstones are formed when molten lava containing iron or iron oxides cools and is magnetised by the earth’s magnetic force. When the lava is molten, it does not exhibit magnetic properties. But when it cools, the tiny molten particles of iron twist around to align with the earth’s magnetic poles and are trapped in this position when the iron solidifies.
It is not clear how the earth became a magnet but it is believed that the earth’s magnetic force is mostly generated by spinning molten iron within a planet that is also spinning. The magnetic stone found in nature is primarily composed of iron and oxygen. They are found in abundance. Artificial magnets though had to be made by man as science needed magnets in different shapes and varying strengths for a variety of purposes from healing to serious experimentation.
Magnets remained one of nature’s mysteries for thousands of years. The only magnets available for a long time were the natural magnets and they were used as compasses. Then, in the 19th century, batteries were developed and a connection between electric current flow and magnetism was discovered. One discovery led to another.
Finally, it was conclusively proved that two wires conducting current and placed side by side will attract each other if the current is in the same direction, or repel if the currents are in the opposite direction.
It was also found that by shaping wire into a coil, the magnetic force around each wire segment would add up to produce a concentrated magnetic force in the centre. These coils were called electromagnets. It was then discovered that the magnetic force in the centre of a coil could be increased by placing a piece of iron inside the coil.
Once placed inside a coil, a piece of iron would still hold its magnetic force for a while after the current in the coil was turned off. This was a great discovery. It meant that magnets could now be artificially made. This discovery changed the course of scientific investigation. It leapfrogged generations and new vistas suddenly opened in the world of magnetic applications.
The discovery of electromagnets led to permanent magnets. Magnets are alloys made by adding different metals to finely ground iron, heating the mixture to melting point and then pouring it into moulds of different shapes. Magnets are given an initial magnetisation while still in the molten form but after they are cooled and hardened, they are demagnetised. Prior to being sold at various distribution points, they are remagnetised at room temperature.
Manufactured magnets are much stronger than loadstones. All artificial magnets use iron as the primary ingredient. Iron has 26 electrons. Within the iron atom are a few electrons that are free to change their spin orientation. When external magnetic forces are applied, these new electrons in each atom will align with the applied magnetic force. The aligned magnetic spin fields of adjacent atoms reinforce each other. When enough electrons in enough atoms are organised in this manner, the iron or iron alloy manifests the property we call magnetism.
Magnets can be made in three ways:
One method is by repeated rubbing on a material which can absorb the magnet’s power. The other method is theone we just mentioned – the electrical method. But there is a third method too and that is with an instrument called the Magnetiser, which can charge the magnetic material instantly without the use of any wires. It is in vogue in many parts of the world.
Artificial magnets are of two types: permanent magnets and electro-magnets. Permanent magnets remain magnetised permanently once they have been fully charged with electric current. Electro-magnets work only when they are connected with electricity.
All magnets, regardless of size, have two poles – the North Pole and the South Pole. If a large magnet is cut into pieces, each piece will become an independent magnet with poles at either end. The poles are actually the concentrations of magnetism at the two ends of a magnet. Magnetic power is at the highest at the two poles and lowest at the point equidistant from the poles.
Opposite poles attract each other and like poles repel. This proves that the two poles differ in nature and in therapeutic effect too. Magneto-therapy is based on the properties of these two poles.
These poles, it has been discovered, also have different biological effects.
For healing, though, the strength of the magnet is less important than choosing the correct polarity. But how do we measure the strength of magnets?
A magnet exerts a twisting and pulling force on some of the electrons in iron atoms. Since the electrons are bound in atoms, they aren’t free to jump out. So the entire piece of iron moves towards the magnet. The force of attraction is called a gauss after the German mathematician Karl Fredrick Gauss. So gauss strength is actually the pulling force measured at the surface of the magnet.