Ask anyone about magnetism and they’ll know, more or less, what it is. They’ll tell you that it is a force that some materials have that can attract bits of iron and steel. This is true, but it is only part of the picture. That everyday definition – or rather description – of magnetism applies only to what a physicist would call ferromagnetic materials.
Ferromagnetism is a term that applies both to materials that are magnetic in nature (lodestones) and those that have been artificially created. It is actually very easy to turn apiece of hard iron or steel into a magnet by subject surrounding it with a coil and applying electricity to the coil. This creates an electromagnetic. When the power is switched off, the hard iron or steel retains the magnetism.
Just as a matter of interest, soft iron and steel does not retain the magnetism when the power is switched off. But soft iron and steel are easier to magnetize and are thus used very commonly in electromagnets. (Remember that scene in Goldfinger where the bug is killed by Odd Job in the car and then the car is crushed and finally the crushed remnant of the car is hoisted into the air by a crane with a giant electromagnet?
In contrast, hard iron and steel are harder to magnetize, but when they are magnetized, they retain their magnetism a whole lot better. This is the subject of a recent blog by Magnetic Therapy Bracelets.
But both permanent and electromagnets belong to a sub-class of magnetism called ferromagnetism. The ferro in “ferromagnetism” comes from the Latin word Ferrum, meaning iron. Iron was the first substance in which magnetism was noticed – because it is so abundant in nature. But there are other ferromagnetic elements around, like nickel and cobalt.
Strictly speaking, any material that can become magnetized into a permanent magnet qualifies as ferromagnetic. But though iron and nickel are abundant, there is not a great deal of variety when it comes to the number of different types of material in nature that are ferromagnetic.
Of those that there are, Iron is the most common, if only because it is the second most abundant metal in the earth’s crust (after aluminium). Indeed it is the fourth most abundant element in the planet’s crust. Perhaps more importantly it is the most abundant element in the planet because the earth’s core is made of iron.
This is perhaps more important because the earth’s core is molten and spins with the planet, but at a different rate. This is what gives the planet its magnetic field, it’s magnetosphere and, of course it’s magnetic poles. If you understand the importance and prevalence of magnetism, then you can understand why it is of interest to those in the health community.