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1. USA Test Prep Activities completed
by Tuesday, March 10
2. Summative Assessment over
Electricity and Magnetism on
Tuesday, March 10
SPS10. Students will investigate the properties
of electricity and magnetism.
 Investigate applications of magnetism
and/or its relationship to the movement of
electrical charge as it relates to
electromagnets, simple motors, and
permanent magnets
Why are some
substances magnetic
and other substances
are not?
Key Idea
A magnet is an object
that is surrounded by a
magnetic field and that
has the property of
attracting iron.
The spinning electrons in
every atom produce tiny
magnetic fields. In most
materials the fields of atoms
point in random directions so
the magnetic fields cancel
each other out.
In some materials
the magnetic
fields of electrons
align with one
another. A cluster
of atoms with
magnetic fields
lined up in the
same way is
known as a
magnetic domain.
How is a magnet made?
For an object to be magnetic,
most of its domains (tiny
magnetic fields produced by
spinning electrons) must be
aligned in the same
direction.
Before magnetization
After magnetization
A pole is the area of a magnetic where
the magnetic effect is the strongest.
Every magnetic has two poles – often
called the north and south pole.
Magnets can produce:
An attractive force (pulling) when unlike
magnetic poles attract
A repulsive force (pushing) when like
magnetic poles repel.
Sounds a lot like the Law of Charges!
Magnetic force is
caused by a magnet
attracting (pulling)
or repelling
(pushing) other
magnets and some
other materials (e.g.
iron and steel)
3. A magnetic field is
area around the
magnet in which
magnetic forces act;
concentrated into a
pattern of lines that
extend from the
magnet’s north pole to its
south pole.
Magnetic energy
results when an
object is moved a
distance by a
magnetic force.
Two Kinds of magnets a) Temporary - easy to
magnetize and demagnetize
easily
b) Permanent - hard to
magnetize or demagnetize
Why does a compass point
to the Earth’s North Pole?
Why does a compass point
to the Earth’s North Pole?
A compass points to the Earth’s
North Pole because the Earth acts
like a giant magnet.
Earth has a north magnetic pole
and a south magnetic pole.
A compass can be used to
find directions because its
needle lines up with the
Earth’s magnetic poles.
Consider the following:
What would happen to the
magnetic properties of a
bar magnetic if you cut it
into two pieces?
You would
have two
magnets, each
with its own
north and
south pole.
How can a magnet lose its magnetic
properties?
a) Dropping a magnet or hitting it too hard
b) Putting magnet in opposite field for too
long
c) Increasing the temperature
Key Idea
An electromagnet is a coil of
current-carrying wire that acts
as a magnet that can be turned
on and off.
Solenoid = a current-carrying coil of
wire with many loops.
When a solenoid is turned on, a magnetic
field is created.
If a piece of iron or other ferromagnetic material
is wrapped by the coils of wire in a solenoid, a
magnet is created when the current is turned
on.
The strength of an electromagnet
can be increased by:
1) Increasing the electric current in
the solenoid
2) Increasing the number of coil
loops around the ferromagnetic
material
3) Using a stronger ferromagnetic
material (more iron content)
Examples of Electromagnet Uses:
a) A doorbell or an alarm
Examples of Electromagnet Uses:
a) A doorbell or an alarm
b) Moving junk cars
Examples of Electromagnet Uses:
a) A doorbell or an alarm
b) Moving junk cars
c) Recording data on your
computer
d) Reading the magnetic strip on
the back of a credit card
Examples of Electromagnet Uses:
a) A doorbell or an alarm
b) Moving junk cars
c) Recording data on your
computer
d) Reading the magnetic strip on
the back of a credit card
e) Electric motors
Big Idea about
Electricity and Magnetism
Electromagnetism - interaction
between electricity and magnetism
Big Idea about
Electricity and Magnetism
a. Magnetic forces arise from the
movement of electrical charge.
b. Electrical forces arise from the
movement of a magnet (induced
current)
Motors
An electric motor is a device that
changes electrical energy into
mechanical energy.
All electric motors have an armature—a
loop or coil of wire that can rotate. The
armature is mounted between the poles
of a permanent magnet or electromagnet.
Generators
A generator is a device that uses
electromagnetic induction to change
mechanical energy into electrical
energy.
An electric current is made when a
magnet moves in a coil of wire or when a
wire moves between the poles of a
magnet (electromagnetic induction).
1. Why are some substances magnetic?
2. What happens if you cut a magnet in
half?
3. Name three uses of magnets in everyday
life.