What an interesting and difficult question you
have asked! I will try to answer it but if you do
not understand everything, don't worry. You will
learn more about these difficult scientific
concepts when you are in 7th and 8th grade.
You know already from experience that when you
bring paper-clips near a magnet they cling to it.
But when you bring wood, glass or plastic near a
magnet nothing will happen.
Why do some materials have strong magnetic
fields while others do not? The magnetic
properties of a material depends on its
atoms. All matter is made up of atoms. The
center of each atom is called a nucleus. Protons
are particles inside it. Around a nucleus are
electrons, which are negatively charged. An
electron moves around a nucleus and it produces a
magnetic field by doing so. This makes every atom
a tiny magnet. But in most materials the magnetic
fields point to different (random) directions. The
result is that the magnetic fields cancel each
other out and the material is not magnetic.
In certain materials however the magnetic
fields of many atoms are aligned with one another.
This means they build little domains where a
cluster of atoms all have their magnetic field in
the same direction. If the material is not
magnetized, all the domains will point in
different directions. But you can magnetize the
material and have all domains arranged in the same
direction. Now you have a magnet.
This means a material can be a magnet if it is
able to form magnetic domains. These materials are
called ferromagnetic. Iron, cobalt and
nickel are good examples.
Back to the paper clips. They are made of steel
which is mostly iron. The magnet causes the
domains in the clips to line up so that the clip
becomes a magnet. After the magnet is removed the
domains return to their random arrangements and
the clips are no longer magnets.
I hope you get the main idea. Please let me
know if you have more questions.
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