Download Electricity and Magnetism

CHAPTER 13
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Atoms are the tiny building
blocks of everything
Almost all atoms have 3
different particles
 Positive charge (+)
 Negative charge (-)
 No charge
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Matter has the same amount
of positive as negative
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Charged particles move between objects
that are close to each other
Static electricity – happens when positive
and negative charges no longer balance
Static means “not moving”
Moving charges create electricity
They also change into sound, light,
and heat energy
Charged particle move between storm
clouds
 Positive particles are near the TOP
 Negative particles are near the
BOTTOM
 The static electricity is released as
Lightning
 Lightning also creates a mighty sound
– thunder
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You can PREDICT this
 If two objects have opposite charges
(+ & -) they will pull to each other
 Electric force – is the pull or push
between objects that have a different
charge
 A charged object can attract something
that has no charge
 If two objects have same charges (+ &
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(+)
PULL
(-)
PULL
(+)
(-)
(+)
(+)
+
-
+
+
Electric field – the space around
electrically charged objects
 It is invisible
 But scientist will draw lines to represent
it
 Strongest closest to the object and get
weaker as it moves away
 A POSITIVE electric field attracts
NEGATIVE charges and pushes away
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Electric current– electric
charge in motion
They flow from one place to
another
It travels QUICKLY and
INVISIBILY
The flow of electric charge
is not the same in all
materials
DO NOT CHARGE EASILY
 Electric charges move SLOWLY
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 Plastic
 Rubber
 Glass
 Dry wood
CHARGED MORE EASILY
 MOVE QUICKLY
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 Copper Wire
 Silver
 Most metals
Circuit – a loop where electric travels
 DOES NOT HAVE ANY BREAKS
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Has opening or breaks where the
electricity will stop following
 MOVE SLOWLY
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Resistance – means the material does
not allow electric charges to flow
through it easily – the wire gives off
light
SERIES CIRCUIT – electric charges
can flow in only ONE path
 Electric charges flow in a single loop
 All bulbs receive the same amount of
energy
 If one bulb “burns out” it acts like an off
switch
 NOT USED A LOT
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PARALLEL CIRCUITS - has two or
more paths for the electric charge to
flow
 There are little loops on the big loops
 Each loop is a separate path for the
electric charge
 A break DOES NOT shut off the
electric of the whole loop, just the small
loop
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Magnet – anything that
attracts other things made
of iron, steel, and certain
other metals
 Magnetism – is a force that
acts on moving electric
charge and magnetic
charges that are near the
magnet
 Magnet comes from
Magnesia (a place in Turkey
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Magnetic field –
invisible field around
the magnet, goes out
in all directions
 Its shape depends
on the shape of the
magnet
 It is STRONGEST at
the magnets “pole
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All magnets have two poles –
NORTH & SOUTH
 Opposite poles have opposite
charges
 Unlike charges attract each
other
 Like charges repel (push)
 IF you break a magnet in two
you will then have 2 magnets
with 2 poles (4 poles in total)
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Earth behaves like a large
magnet
 Like a magnet, it has the
strongest
pull at its poles
 The Earth’s poles are no the
same as the geographic
poles
 The magnetic NORTH pole is
in Canada
 The magnetic SOUTH pole is
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Compass – a
helpful tool that
help you find
directions
The needle will
always point you
in the direction of
north
If you are near a
magnet, the
compass will not
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Invented by Hans Christian Oersted
Electricity and magnetism are closely related
Both are results of charged particles moving
We use them a lot in our daily lives
Electromagnet – is a coil of wire with many
loops through which an electric current
passes
To make the field stronger it is wrapper
around copper
Can be a VERY POWRFUL MAGNET
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Used in industry to lift heavy
materials
Complex machines used by
doctors and scientists
Are a part of many
electronic gadgets:
 Televisions
 Fans
 DVD players
 Doorbell
 A motor
 Earphones
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The power of magnetism can be
transformed into the power of electricity
This helped make electric, motors, and
generators
 When a magnet is moved, its magnetic
field moves with it
 Changing a magnetic field generated
electricity
 More loops = stronger
 Faster = stronger
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1831 – Michael
Faraday invented a
machine that used
magnets to transform
motion into an electric
current
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Turning a crank
Used in emergency
flashlights and radios
Most homes, school, and businesses
today get their electricity from
generators
 Generator – is a machine that creates
electric energy by turning coils of wire
around powerful magnets
 Uses magnets and wires to turn
mechanical energy into electrical
energy
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1740s – Benjamin
Franklin describe positive
or negative
1829/1831 – Joseph
Henry and Michael
Faraday produce a current
by changing a magnetic
field
1879 – Thomas Edison
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Many ways for a
generator to produce
electrical energy
Wind power – a wind
turbine changes the
energy of the blowing
wind into electricity
Hydroelectric Power – the
power of falling water is
changed into electricity by
generators near Niagara
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If you are not careful, electricity
can case a serious shock or start
a fire
Respect the power of electricity
Read and follow the instructions
that come with every electrical
produce
Replace worn or cracked
electrical product
Relocate, or move, appliance
cords so people will not walk on
or trip over them, and children or