As children we have all had an “attraction” to magnets; it was one of our special toys! Besides attracting us, we all know that it was capable of physically attracting certain metals such as iron. As we grew up, it graduated from being a ‘fun toy’ and became an integral part of many of our science experiments. And, we discovered more and more about this wonder element!
Today, magnets are present in all our homes; just not in the form we played with as children! It is present in our laptops and computers, in our refrigerators, our music players, telephones, vacuum cleaners – you name it! Most of our electrical and electronic gadgets comprise this super component in some form.
Man has known magnets for over two centuries now and there are several stories as to its discovery. There is a story of a shepherd who is believed to have accidentally discovered it while herding his flock. His crook, which was made of iron, was attracted to a rock. By the way, the shepherd’s name was “Magnes”! Some people also credit Archimedes, who used lodestones to pull out the nails in an enemy’s ship and sink it, as the discoverer of magnets.
The earliest forms of magnets were known by the name lodestone or magnetite. Did you know that the earth’s ocean floors contain magnetite? And these are believed to be around 2 million to 55 million years old!
Our earth, in itself, is considered one huge magnet. All negatively charged materials are pulled towards the North Pole and all positively charged material are attracted to the South Pole. The magnetism of earth is sometimes affected by the changes in the liquid iron that sits in the Earth’s core!
In the beginning, man produced magnets by rubbing iron on lodestones. The friction helped to line up the iron electrons, so the attraction would be in the same direction. Today magnets are created with the help of electricity.
Magnets can be made in any shape and can come in any size. There are two kinds of magnets – permanent and induced. The former are also referred to as hard magnets and always have the magnetic force. In the latter, magnetism is created by putting it within a magnetic field. It is also known as soft magnet, because its magnetic feature is temporary.
Did you know that magnets need not always be made of iron, or for that matter, even metal?! Magnets can be created using any material that has unpaired electrons. For example, neodymium – it is used in our disk drives; and spinels, which are used in our refrigerator doors.
The world’s largest magnets can be found in two laboratories – The Los Alamos National Laboratory in New Mexico and the Florida State University (FSU). The magnet in Los Alamos is capable of reaching about 100 tesla while the one in FSU can reach up to 45 tesla. For those who don’t know what that means; tesla is unit of magnetic flux density. Really want to understand its power? Compare this – the magnet in the junkyard that lifts cars is only 2 tesla! Now, do the calculations!
Besides iron and steel, magnets can also be made from other metals such as copper, cobalt, nickel and aluminum.
The discovery of the north and south poles in a magnet was what led to the creation of the compass. And the Chinese are credited with this invention as they used it to navigate the oceans many centuries ago.
Chinese are not the only navigators who used magnets; homing pigeons are also believed to use magnetic sense! Studies have revealed that the magnetite in their beaks help them in navigation.