Magnetism

Magnetism has been known since ancient Greece as the ownership 

of certain minerals such as magnetite (so named because it was discovered 

in the Greek region called Magnesia) to attract pieces of iron. They are natural

 magnets.It appears that it was the Chinese who first used magnets as compasses in the 

twelfth century.Petrus Peregrinus (Pierre de Maricourt), a French crusader, in 1269 found that if

 a needle is left freely on a spherical magnet, it is oriented along lines passing

 through points located at opposite ends of the field. By analogy, states north and 

south poles of the magnet, and found that the north pole andsouth pole attract, like poles repel it, and that the fragment a piece of magnetite, 

magnetic poles are still appearing.Magnetite crystalsIn the s. XVI, William Gilbert (physician to Queen Elizabeth), artificial magnets

 produced by rubbing pieces of iron and magnetite. He also suggested that the

 operation of the compass was due to the magnetic properties of the Earth.There are some creatures that have magnets inside that work like compasses.

 It is called magnetism. It seems that this phenomenon is the ability to orient migrating birds.Some bacteria naturally synthesize grains of magnetite (iron oxide, Fe3O4 formula)

 with a single domain, which are aligned and give rise to microscopic compass,

 allowing them to navigate.Found magnetite crystals inside the skull of the pigeon, connected to many nerves.

As a result, the pigeons know longitudinally oriented magnetic field, ie north-south 

and east-west, as well as the latitude, ie according to the inclination of the field. Also

 magnetic substances have been found in other organisms such as bees, monarch

 butterflies, moles, turtles and even in human brain tissue.One of the many applications of magnetic fields are the magnetic stripes on credit 

cards, phone ... They keep the information through the tiny magnetic domains. The 

reader consists of a small coil which induces an electric current to the passage of

 the card. So often damaged the card when it comes to intense magnetic fields.In ancient times the magnetite attributed many properties. Was supposed to cure

 rheumatism and gout and allowed to speak with the gods. In the sixteenth century

 Paracelsus tried to use magnetism to cure diseases, but accomplished nothing. 

All its supposed successes were due to placebo effect. Even today we are also 

trying to sell magnetic bracelets and other devices as a remedy for many ailments, 

but there is no scientific evidence of its benefits