Transcript Magnetism Notes

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Investigate applications of magnetism and its
relationship to the movement of electrical
charge as it relates to
• electromagnets
• simple motors
• permanent magnets
• electromagnetic induction
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Magnetism is the
force of attraction or
repulsion due to
electron motion.
Magnets have two poles, a north
pole and a south pole.
Unlike magnetic poles attract each other, while like magnetic poles
repel each other.
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5Groups of atoms with magnetic poles
aligned are called magnetic domains.
Materials
with most of
the domains
lined up are
considered
magnetized.
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The more domains that
are aligned, the stronger the
magnetic field in the
material.
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Field lines were introduced by michael faraday ,
who named them ‘’lines of force.’’
Sketch
this one
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Magnetism From Electricity
A connection between electricity and magnetism was discovered (accidentally) over
100 years ago, it was noticed that a compass needle is deflected when brought into the
vicinity of a current carrying wire. Thus, currents can induce a magnetic field.
An electromagnet is simply a coil of wires which, when a current is passed through,
generate a magnetic field, as below.
Current gives rise
to magnetic fields,
just as electric
charge gave rise to
electric fields
Electromagnet
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The basic idea behind an
electromagnet is extremely
simple: By running electric
current through a wire, you can
create a magnetic field.
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Electricity through the coiled wire
creates a magnetic field which induces
magnetism in the iron core. The domains
in the core become aligned with the
magnetic field of the coil.
Electromagnets
12 A rotating electromagnet is used in
an electric motor to convert electrical
energy to mechanical energy.
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•When a magnet is moved near
a wire, an electric current
can be created.
•This process is called
electromagnetic induction.
• Electromagnetic induction
is used in the operation of a
generator, a device that
converts mechanical energy
to electrical energy.
•In a generator, an
electric current is
produced when a coil of
wire is rotated in a
magnetic field.
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Generating
electricity:
•coil of wire
rotated in a
magnetic field
•magnet is
moved near a
wire
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The use of magnetic waves to make pictures of the inside of the
body. Using a large magnet, radio waves, and a computer, an MRI
produces two-dimensional and three-dimensional pictures.
July 3, 1977
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Which of these correctly
identifies both devices
illustrated?
A Picture A: electric generator;
Picture B:electromagnet
B Picture A: electromagnet;
Picture B: electric motor
C Picture A: electric motor;
Picture B: electromagnet
D Picture A: electric generator;
Picture B: electric motor
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A magnetic field can be found in which
of the following?
A electric motor
B sound wave
C plastic cord
D glass rod
Aurora Borealis
An electric discharge through the atmosphere connected with magnetic
disturbance. Most aurora are green and red emission from atomic oxygen.
Molecular nitrogen and nitrogen ions produce some low level red and very high
blue/violet aurora.