Download 2-2-1 Magnetism notes

Magnetism
What is Magnetism?


Magnetism is a property which makes
certain materials attract or repel a
magnet.
Comes from “magnetite”, a mineral first
found in Magnesia, Asia Minor.
All objects fall into one of
three categories:
1)
2)
3)
Magnetic objects: display all properties
of magnetism.
Non-magnetic objects: unaffected by
magnets
Ferromagnetic objects: can temporarily
become a magnet. (Iron, Nickel, and
Cobalt are the only ferromagnetic
substances)
Some Properties of Magnets
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Every magnet has 2 poles, labeled North
and South.
Opposite poles attract, like poles repel.
They will do so because of the “magnetic
field”: an area around a magnet where
forces are felt. We can draw magnetic
fields using “lines of force”
Drawing Magnetic Fields
Bar Magnet
N
S
Drawing Magnetic Fields
U Magnet
N
S
Drawing Magnetic Fields
Interaction between like poles
N
S
N
S
Drawing Magnetic Fields
Interaction between opposite poles
N
S
N
S
The Earth’s Magnetic Field

The Earth is a big magnet. Given the rules of magnetic
attraction, what magnetic pole is found where Santa
lives (the “north pole”)
The Earth’s North
geographic pole is
actually a SOUTH
magnetic pole
because the north
end of a magnet is
attracted to it!
Electromagnetism

All phenomena resulting
from the interaction
between electricity and
magnetism.
Magnetic field of a live wire
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Discovered by Hans Christian Oersted
Only happens when there is a current
in the wire.
Right hand rule
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Your thumb points in the direction of
the conventional current flow.
Your fingers show the direction of the
magnetic field lines.
Right hand rule
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