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Magnetism
What is magnetism?
 Magnetism is the force of attraction between magnets and
magnetic objects.
Characteristics of Magnets
 All magnets have a North and a
South Pole.
 All magnets have a magnetic field
around them.
 The magnetic field is a line of force
running from the north-seeking pole
to the south-seeking pole of the
magnet.
Earth’s Poles
 In our planet we have the North and South Poles.
 Earth acts like a giant magnet and is surrounded by a magnetic field.
 Earth’s magnetic field is what causes the needle of a compass to
point in different directions and causes the poles of a magnet to
point either North or South.
Attractive Magnets!!!
 The north and south poles of two magnets attract each
other. They always need to be opposite poles to be
attracted.
 The magnetic force pulls them together.
 Magnets of the same pole will repel each other, either two north
or two south poles.
Magnets and electricity
 Magnetic fields can be created with batteries, bolts and
wire.
Magnets and Electricity

Electricity and magnetism are related:
1. An electric current produces a magnetic field.
2. A change in a magnetic field can produce an electric
current.
Magnets and Electricity

The strength of an electromagnet can be increased by:
1. Increasing the number of coils.
2. Increasing the voltage of the current.
Magnets and Electricity

Electromagnets are used in every day life:
1. In telephones, electric motors, generators, televisions,
door bells.
2. You can see a huge electromagnet in action in a junkyard.
A crane holding the electromagnet can be used to pick up
metal pieces when current flows through it. When the
crane operator wants to drop the scrap, he or she will
simply shut off the current to the electromagnet.
How many poles do
magnets have?
What happens when
two magnets of
different poles are put
close together?
What happens when
two magnets with
same poles are put
close together?
What is the area of a
magnetic force called?
Electric current creates a
_____________ field.
magnetic
What do you make if you put together a
closed circuit and wrap the wire around an
iron bolt?
Electromagnet
How can you make an
electromagnet stronger?
You can wrap the wire around the
iron bolt more times.