ELECTROMAGNETS

```Teacher Resource Sheet EEM - 15
INVESTIGATING ELECTROMAGNETS
General Recommendations
1. If students are getting negative readings for the magnetic field data, reverse the
connections on the battery.
2. The use of battery holders is recommended.
3. Batteries will quickly heat up and lose energy if left connected to the electromagnet.
Be sure that students are aware of this. Students should disconnect the battery after
each trial is performed.
4. You can use Vernier Middle School with Computers 3rd Ed. Activity 28,
“Electromagnets,” as a reference for this investigation.
5. You may prefer to have students predict the graph in this investigation using
LoggerPro. To access this function, click on the Analyze menu and select Draw
Prediction. At this point, students can use the mouse of the computer as a pen and
can sketch a curve directly on the graph.
Guidelines for Students’ Independent Investigations
In the next series of investigations, groups of students will explore a variety of variables
that can affect the strength of the magnetic field generated by an electromagnet. All
students should investigate question 1 in order to become familiar with the Logger Pro
equipment.
The questions are listed below along with suggestions for each investigation.
1. How does the number of wraps of wire in an electromagnet affect the strength of
the magnetic field?
 Use single strand rubber or plastic coated copper wire – 22 or 24
gauge cut in 1m lengths. Strip away about 1cm of the coating from
each end.
2. How does the amount of current flowing through an electromagnet affect the
strength of the magnetic field?
 Use a rheostat or different sized batteries to create different currents.
 Place an ammeter in series with the electromagnet in order to quantify
the strength of the current.
3. How does the composition of the core affect the strength of the magnetic field?
 Use any available materials such as carbon rods, metal strips, glass
rods, dowel rods, density cylinders … etc.
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Teacher Resource Sheet EEM - 15
4. How does the mass of the iron core affect the strength of the magnetic field?
 Use increasing numbers of iron nails to increase the mass of the core.
 Use a triple beam balance to quantify the mass.
5. How does the metal in the wire affect the strength of the magnetic field?
 Use copper, brass, aluminum, steel, multistranded … etc. coated wire.
6. How does the presence or absence of coating on the wire affect the strength of
the magnetic field?
 Use plastic or rubber coated wire, annealed wire, and uncoated wire.
Be sure to keep diameter and composition constant.
7. How does the diameter of the wire affect the strength of the magnetic field?
 Use a range of diameter wire. Use caution with smaller diameter of
wires as they will heat up very quickly.
Students will work as a class to investigate question 1 and use the procedure as a model.
Next, students will work in teams to design an investigation to explore one question from
numbers 2 through 7. Students will be provided a general procedure for collecting and
analyze magnetic field strength data using the LoggerPro software. You may choose to
provide a list of materials for use by each group.
After conducting the investigation, students will create a 3 minute presentation and share
findings with the class. Students should be encouraged to use available technology such
as tablets, LCD projectors, and computers to present information. During the
presentation, students will record information that they will use to design an
electromagnet (Analysis #1). After hearing each presentation, students with then design
an electromagnet that could be included in the ROOM PROTECTOR with the strongest
magnetic field possible using materials from the various investigations. (Learning Log
Entry)
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