When were magnets made and why it sticks to objects made with metal?

Roughly around 4,000 years ago a Greek shepherd named Magnes was reported to have been tending his sheep in a region of northern Greece called Magnesia.

He took a step and unexpectedly realized that the nails that held his shoe together and the metal tip of his staff were stuck fast to the rock he was standing on! Curiously, he began digging and discovered the first recorded lodestone. Lodestones were henceforth known as 'magnetite,' probably named after Magnes or Magnesia.

A magnetic field is always produced by moving charges.

In many substances, equal numbers of electrons spin in opposite directions, which cancels out their magnetism. So they are not influenced by the magnetic field.

In metal like Iron, there are unpaired electrons which allow them to become magnetised.

Magnets attract iron due to the influence of their magnetic field upon the iron. Before a piece of iron first enters the magnetic field of a magnet, the motion of the iron's electrons is random. 

As it is exposed to the magnetic field, the atoms of the iron begin to align their electrons with the direction of the magnetic field, which makes the iron magnetized as well.

This, in turn, creates an attraction between the two magnetized objects.

Materials that are not attracted to a magnet like plastic have a permeability of, essentially, 1.  There is no magnetism induced in them by an external magnetic field, and therefore, they are not attracted by a magnet. 

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Updated on: 10-Oct-2022

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