Download Magnetism and electromagnetism How are magnetic poles

Magnetism and electromagnetism
How are magnetic poles
and electric charges
alike? How do they
differ?
What subatomic
particle’s spin causes
magnetism?
What is an area of a
substance with aligned
spins called?
What substance is easy
to make magnetic?
Figure 1
Magnetic poles, like electric
charges, can _________ or
__________. Magnetic poles are
different than electric charges
because electric charges can exist
_________, a positive charged
object or a negative charged
object, but magnetic poles always
exist in ___________.
Objects can be magnetically
charged based on the alignment of
spinning _____________ in a
substance. Areas with the
majority of electrons spinning in
one direction are called
_____________. In a nonmagnetic substance the _________
are random while in a magnetic
substance domains are _________.
___________ is a substance whose
____________ can be easily
aligned while other substances,
like wood, do not have _________
that can be _____________.
In which direction are
magnetic field lines
drawn?
Figure 2
What is the needle on a
compass?
If we picture the earth as
a big magnet, which
magnetic pole would be
in the arctic?
Magnetic fields outside of objects
are said to go from the _________
pole to the _________ pole. The
magnetic field around a bar
magnet and a horseshoe magnet
are shown below using magnetic
field lines. The ________ the
magnetic field lines are to one
another, the ___________ the
magnetic field.
The _________ pole of a compass
needle (really a little magnet) is
attracted toward a _________ pole
of another magnet, remember
opposites attract.
Because the ________ pole of the
magnet in a compass is attracted to
the top of the earth, the top of the
earth acts like the __________
pole of a bar magnet.
Magnetic field lines
outside a magnet are
always drawn from
________ to ________.
Figure 3
What can create
magnetism in a wire?
What is the shape of the
magnetic field around a
current carrying straight
wire?
So the _______ pole of the earth is
called a _______ pole because the
_________ pole of the magnet in a
compass is attracted to it, not
because the _________ pole of the
earth is like the _______ pole of a
magnet. Notice that when the
earth is drawn as a magnet the
magnetic field lines go from
_________ pole of the magnet to
_________ pole of the magnet just
as we saw with the bar and
horseshoe magnet.
Magnetism is also created when
__________ move through a wire.
All the __________ are moved the
same way so all of the spinning
_____________ line up.
The magnetic field is
_____________ around the wire.
How can the magnetic
field around a wire be
determined?
What is the difference
between electron flow
and current?
Left hand rule- (For a straight
wire) If you point the _________
on your left hand in the direction
of electron flow, your __________
will wrap around the wire in the
direction of the magnetic field.
The rule changes to a right hand
rule if current instead of electron
flow is known because current is
opposite to electron flow.
Figure 4
Left hand rule for electron flow
Right hand rule for current
In some diagrams of electrical
equipment it is necessary to "cut"
conductors so that you view them
from the ends. In such cases, it is
impossible to use arrows to
indicate the direction of electric
flow. Instead, you use a system of
________ and ____________.
How is current or
electron flow indicated
for “cut” conductors?
(Here we’ll just do
current)
The DOT (figure A below)
indicates the current to be flowing
___________ of the conductor
(TOWARD you) . The CROSS
(figure B below) indicates the
current to be flowing __________
the conductor (AWAY from you) .
Think of the DOT as the "point" of
the arrow coming OUT of the
wire, and the cross as the "tail" of
the arrow ENTERING the
conductor.
Figure 5
Draw magnetic field lines around each “cut” wire diagram below
A coil of wire with electricity
flowing through it will create a
magnetic field similar to the field
that surrounds a permanent bar
magnet
How can the left hand
rule be used to find the
magnetic north pole of a
coil of wire with moving
electrons?
What happens to the rule
if current instead of
electron flow is known?
2nd left hand rule – (for a coiled
wire) If you point your ________
in the direction the electrons are
moving around the coil, then your
____________ will point to the
magnetic __________ pole. The
rule changes to a right hand rule if
current instead of electron flow is
known because current is opposite
to electron flow.
Figure 6
How will the two coils in
Figure 6 react to each
other when electricity
flows through them?
What is a magnet created
with electricity called?
How can the strength of
an electromagnet be
increased?
Magnets created using electricity
are called __________________.
 More _________ would create
a ____________ electromagnet
 More ______ in the _____ will
create a _______ electromagnet
 Adding an _____ _______ will
create a _____________
electromagnet
Figure 7
What will happen to the
iron core of an
electromagnet after the
current is stopped?
If the core of an electromagnet is a
piece of _______, then it will
retain ___________ properties
even after the current is stopped.
How can magnetism in
the iron be destroyed?
The magnetism can be destroyed
by ___________ the iron or by
_____________ it on the ground.
Electricity can create magnetism,
magnetism can create electricity
What is created when a
magnet is moved
through a coil of wire?
When a magnet is passed through the
middle of a coil of wire, the magnet
pushes or pulls the _____________ in
the wire creating a ___________.
Figure 8
Here the magnet is being pushed into
the coil. The ammeter shows current
____________ in a positive direction.
Figure 9
Now the magnet is stationary inside the
coil. There is no current produced in the
coil, shown by the zero on the ammeter
Figure 10
Finally the magnet is being pulled out.
The ammeter shows current
_____________ in the opposite
direction than before.
If this were to continue we would end
up with ___________ that goes from
positive to negative and back again.
This is called ___________ current and
an AC generator produces this kind of
______________.