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Magnetism
What is Magnetism?

Magnetism is the attraction of
a magnet to another object.
What are Magnetic Poles?
Magnets have two ends,
called magnetic poles.
 Magnetism is strongest at the
poles of a magnet.

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Magnetic Poles

Magnetic poles that are alike
repel each other.
North repels North
 South repels South


Poles that are not alike attract
each other
North attracts South
 South attracts North

What is a Magnetic Field?
The magnetic force exerted in
the region around the
magnet is the magnetic field.
 This allows magnets to
interact without touching.

What are Magnetic Field Lines?

Magnetic Field Lines spread
out from one pole, curve
around the magnet, and
return to the other pole.
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What do atoms have
to do with it?
All atoms have magnetic
fields because of the charged
particles inside.
 Most atoms’ magnetic fields
point in random directions, so
they all cancel each other
out.

What do atoms have
to do with it?
In magnetized material, all or
most of the magnetic fields
are arranged in the same
direction.
 A material that keeps its
magnetism is called a
permanent magnet.

What do Electric Currents
have to do with Magnets?
An electric current produces a
magnetic field.
 The direction of the current
determines the direction of
the magnetic field.

What are the magnetic
properties of the Earth?

The Earth has an immense
magnetic field around it
called the magnetosphere.
What is an Electromagnet
An Electromagnet is a strong
magnet that can be turned on
and off.
 It consists of a currentcarrying wire wrapped around
an iron core.

Characteristics of Electromagnets


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Strength depends on the number
of coils and the size of the iron
core.
The greater the number of turns
the coil has the stronger the
magnet will be.
The closer the coils are the
stronger the magnet will be.
Motors and Generators


Electric Motor – a device that
changes electric current into
mechanical energy.
Generator – a device that
changes mechanical energy
into electrical current.