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Inquiry Activity
Exploring Electromagnets
**This activity can be done individually or used as an extension to the Exploring
Magnets activity. ** (Duration = 50min.)
Purpose: The students will be able to construct an electro-magnet, observe what
properties strengthen the magnetic field of an electromagnet, and
observe the attractive and repulsive forces on a magnet.
Standard Covered:
8.3.18 Investigate and explain that electric currents and magnets can exert a force
on each other.
Materials Needed:
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(For each group)
1, 1.5, and 2 feet of thin plastic covered wire, copper core or stranded.
Masking tape or scotch tape
Several different sized nails
A pencil and pen
A nine volt battery and a AA battery.
A Bar magnet
Several different sized paper clips.
Introduction:
Magnets produce a magnetic field that go out of the
north pole of the magnet and into the south pole of the magnet.
This kind of magnetic field is known as a magnetic dipole. (See
diagram on right) Magnets are not the only things that can
produce magnetic fields. Moving charged particles such as
electrons can also create a magnetic field. A straight line of
moving electric charge, in a wire, creates a magnetic field which
is composed of concentric circles around the wire. (See diagram
on left) Electrical current is the term used to describe
electrons moving through a wire. If the current is turned off
and there is no longer any moving charge the magnetic field
surrounding the wire will immediately vanish, unlike a
magnet whose magnetic field is permanent or semipermanent. When a current travels through a single coil of
wire a magnetic field similar to the shape of a plump donut
is created. The magnetic field is simply concentric circles around each part of the wire,
but they follow the path of the wire. The more coils of wire with current running
through them in the same direction, the stronger the magnetic field that is created.
With a large number of coils, even a small
amount of current can produce a noticeable
magnetic field.
Notice that the
magnetic field of
a large number
of coils closely
resembles a
magnetic dipole,
with both a
virtual north and
south pole. If the direction of the current running
through the coils is reversed, the virtual poles of the
electromagnet are switched. The strength of an
electromagnet can be increased not only by increasing
the number of coils of wire, but by wrapping the coils of
wire around a rod of ferromagnetic material such as
iron or steel. The magnetic field of the electromagnet aligns the tiny magnet molecules
inside the metal core, magnetizing the metal. With the molecules magnetically aligned,
the overall magnetic field of the electromagnet is increased. (It is also easier to make a
simple electromagnet if you have
something to wrap the wire around and
as an added bonus, the magnetic field is
strengthened!) This is why a nail must be
used to make the strongest electromagnet
in the activity. (The picture to the right is
from www. exploratorium.edu)
Procedure:
1. After forming groups of four to five students, review the basic concepts of
magnets: ability to attract certain types of metals, has two poles(north and
south), like poles attract, unlike poles are repelled, and the shape of the magnetic
field surrounding a magnet.
2. Now discuss that you can use electric current traveling through a wire to create a
magnet, called an electromagnet. Distribute the student worksheet, Exploring
Electromagnets, which includes a diagram of a simple electromagnet and
direction to get them started building their own. The purpose is to see which group
can create the strongest working electromagnet.
3. Circulate amongst the groups, helping them to get started, making suggestions if
they are unable to make a workable electromagnet.
**CAUTION** Make sure to tell them that when they are testing their
electromagnets not to connect the battery to the wire for to long, the wire and
battery could get very hot!
4. When each group is satisfied with their constructed, workable electromagnet,
bring the class together and have each group demonstrate the strength of their
electromagnet by trying to pick up a variety of different metal materials that you
have provided. (Example: different sized nails and paperclips)
5. After the class has decided which electromagnet is the strongest, have each
group discuss and write down on the worksheet the differences between their
electromagnet and the strongest electromagnet. Based on their observations of
the construction of the strongest electromagnet, they should write down what
they think is responsible for making an electromagnet stronger.
6. Have them come up with and write down several uses for an electromagnet.
(Remember that unlike a regular magnet, an electromagnet can be turned off.
This is advantageous!)
7. Finally , ask them if they can come up with and write down a way to test if their
electromagnet has a north and a south pole. (Optional:) Explain how
electromagnets work using the content described in the introduction.
Assessment:
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Completion and displayed comprehension of the worksheet.
Extension:
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(Earth Science) A basic understanding of simple electromagnets can be used to
explain the origin of the magnetic field of the earth. Moving electrical charge, or
current, can cause magnetic fields. The earth’s magnetic field is believed to be
caused by exactly that, electric currents inside the earth, a result of the rotation
and spinning of the liquid metallic outer core of iron and nickel. This is known
as the dynamo effect. Further study could involve researching the changing
strength and reversals of the earth’s magnetic field over time.
Internet Resources:
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http://www.wcsscience.com/magnet/madness.html
http://www.exploratorium.edu/snacks/iconmagnetism.html (Great ideas!)
Author: Aaron Debbink
Exploring
Electromagnets
Name: ________________________
Period: _______
Introduction: An electromagnet
can be made by connecting a
battery to a coiled piece of wire.
A coil of wire can be easily
made by wrapping the wire
around something. Your job is
to construct the strongest
electromagnet in the class. You
will compete against other groups later in the period.
Directions:.
1. To get started you need to decide what length of wire you will use, what you are
going to wrap the wire around, and what battery you will use.
2. Construct an electromagnet using the material you have selected.
3. Test the strength of your electromagnet by trying to pick up different sized
paperclips or nails.
4. If your electromagnet does not work try using a different length of wire, a
different core to wrap you wire around, or a different battery.
5. Once you have constructed a working electromagnet, describe below how you
constructed it and what materials you used:
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What was different about your electromagnet and the strongest one of the class?
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Based on the differences, what makes a strong electromagnet? Does it depend on what
is used for the core? Do more coils or less coils of wire strengthen the electromagnet?
What battery should be used?
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What are some potential uses for an electromagnet?
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How could you test your electromagnet to determine if it has both a north and a south
pole?
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