Inquiry Activity Exploring Electromagnets

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18 Οκτ 2013 (πριν από 4 χρόνια και 2 μήνες)

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Inquiry Activity

Exploring Electrom
agnets


**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
prope
rties

strengthen the magnetic field of an electromagnet, and
observe the attractive and repulsive forces on a magnet.





Standard Covered:



8.3.18


Investigate and expl
ain that electric currents and magnets can exert a force
on each other.


Materials Needed:

(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
nail
s



A pencil a
nd

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 fi
eld 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 wir
e,

creates a magnetic field which
is
composed of concentric circles around the wire. (See diagram
on left)

E
lectrical 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 ch
arge the magnetic field
surrounding the wire will immediately vanish, unlike a
magnet
whose

magnetic field is permanent or semi
-
permanent.

When a current travels through a single
coil

of
wire a magnetic field similar to the shape of a plump donut
is crea
ted. 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.
Wit
h 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
magn
etic dipole,
with both a
virtual

north and
south pole. If the direction

of the curr
ent running
through the coils is

reversed, the virtual

poles of the
electromagnet are

switched.
The strength of an
electromagnet can be in
creased 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
electromagn
et 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
mag
nets
: ability to attract certain types of metals, has two poles(north and
south), like poles attract, unl
ike 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
Electromag
nets
, 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 gr
oup 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 differe
nt metal material
s

that you
have
provided. (Example: diff
erent 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 observa
tions of
the construction of the strongest electromagnet,

they should
write down what
they think is responsible for making an electromagnet stronger.

6.

H
ave 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

, a
sk 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
:



Completion and displayed comprehension of the worksheet.


Extension:



(Earth Science)
A basic understanding of simple electromagnets can be used to
explain the origin of the magnetic field of the earth.

Moving el
ectrical 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:



http://www.wcssci
ence.com/magnet/madness.html



http://www.exploratorium.edu/snacks/iconmagnetism.html

(Great ideas!)






Author: Aaron Debbink


Exploring


Name: ________________________


Electromagnets

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 diffe
rent l
ength 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:


__________________________________________________
_________________________


___________________________________________________________________________


___________________________________________________________________________


What was different about your electromagnet and the strongest one of t
he class?


___________________________________________________________________________


___________________________________________________________________________


___________________________________________________________________________



___
________________________________________________________________________




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 b
attery should be used?



___________________________________________________________________________


___________________________________________________________________________


________________________________________________________________________
___



___________________________________________________________________________


What are some
potential uses for an electromagnet
?


___________________________________________________________________________


__________________________________
_________________________________________


___________________________________________________________________________


How could you test your electromagnet to determine if it has both a north and a south
pole?


___________________________________________
________________________________


___________________________________________________________________________


___________________________________________________________________________