Student Resource Sheet EEM - 15
INVESTIGATING ELECTROMAGNETS
An electromagnet is a device that uses electrical energy to create a magnetic field. A simple
electromagnet consists of wire wrapped around an iron core. The strength of the magnetic field
produced by the electromagnet depends on several variables including the number of wraps of
wire, the amount of current flowing through the wire, the composition of the core, the mass of
the core, and the wire type. If you decide to incorporate an electromagnet into the design of your
ROOM PROTECTOR, you will need information about the effect of the different variables on
the strength of the electromagnet.
In the next series of investigations, your class will explore the following questions:
1. How does the number of wraps of wire in an electromagnet affect the strength of the
magnetic field?
2. How does the amount of current flowing through an electromagnet affect the strength of
the magnetic field?
3. How does the composition of the core affect the strength of the magnetic field?
4. How does the mass of the iron core affect the strength of the magnetic field?
5. How does the metal in the wire affect the strength of the magnetic field?
6. How does the presence or absence of coating on the wire affect the strength of the
magnetic field?
7. How does the diameter of the wire affect the strength of the magnetic field?
You will be working as a class to investigate question 1. Then, you will work in teams to
investigate one of the other problem questions. After conducting the investigation, you will
report your findings to the class. Finally, you will design an electromagnet that creates the
strongest possible magnetic field.
Design your investigation using the following information:
CRITERIA FOR A WELL-DESIGNED INVESTIGATION:
• only one variable is tested
• testing conditions such as time, temperature, and surfaces are controlled
• multiple trials are completed
• appropriate materials and equipment are selected
• clear, logical directions are included
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Student Resource Sheet EEM - 15
INVESTIGATION 1: ELECTROMAGNETS
Objective
After completing this investigation, you should be able to
1. identify advantages and limitations of using technology in order to describe the
relationship between the number of wraps of wire in an electromagnet and the
strength of its magnetic field.
Problem Question
What is the effect of the number of wraps of wire in an electromagnet on the strength of its
magnetic field?
Materials
computer
Vernier computer interface
Logger Pro
Vernier Magnetic Field Sensor
large iron nail
insulated wire, 1 m
D cell battery
tape
FIGURE 1
POSITIONING THE SENSOR
Activity 1
1. Read the procedures, “Investigating Electromagnets with a LoggerPro.”
2. Reread the procedures and underline the verbs.
3. Write a hypothesis for this investigation.
If __________________________________________________________________________ ,
then ________________________________________________________________________
because _____________________________________________________________________ .
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4. Sketch a curve on Graph 1 to predict the outcome of the investigation. Pay close attention to
the intervals as you sketch your graph.
GRAPH 1
5. Conduct the investigation.
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INVESTIGATING ELECTROMAGNETS WITH LOGGERPRO
A. Tape a Magnetic Field Sensor to the tabletop. The white side of the sensor (or white
dot) should face up and be parallel to the tabletop.
B. Plug the Magnetic Field Sensor into the computer interface. Set the switch to the
LOW x10 amplification setting. The unit of magnetic field strength utilized by this sensor
is the milliTesla (mT).
C.
Click
to zero the sensor.
D.
Click on the Data Collection button next to the Lab Pro button in the tool bar.
E.
In the Mode window, select “Events with Entry.”
F.
In the Column Name window, type “#.”
G.
In the units window, type the number of winds.
H.
Collect data for zero winds.
a. Click
.
b. Get a large iron nail and place its pointed end perpendicular to the top of the
Magnetic Field Sensor at its very end, as shown in Figure 1, “Positioning the
Sensor.” When the reading has stabilized, click
.
c. Type “0” in the edit box (for 0 winds).
d. Press ENTER. The magnetic field strength value for zero winds is now saved.
I.
Tape one bare end of a 1 m insulated wire to the bottom end of a D cell battery.
J.
Place the nail on the wire at a position 10-15 cm from the battery. Tightly wind the
wire around the nail 3 times as shown in Figure 1, “Positioning the Sensor.”
K. Collect data for 3 winds.
a. Firmly press the other bare end of the wire to the top of the battery.
b. Have your partner touch the pointed end of the nail to the top of the sensor at its
very end as shown in Figure 1, “Positioning the Sensor.” Important: If the
reading decreases, reverse the connections of the wire to the battery.
c. When the reading has stabilized, click
.
d. Type “3” in the edit box (for 3 winds).
e. Press ENTER. The magnetic field strength value for 3 winds is now saved.
L. Repeat Step G for 6, 9, 12, 15, 18, and 21 winds. Caution: The battery will become
warm as it is used. To keep it from getting hot, and to save energy, remove the wire
from the top of the battery immediately after
has been clicked. Important:
Wrap all winds at nearly the same distance from the nail end.
M. Click
to end data collection. Record the magnetic field strength values
displayed in the table in your data table.
N. Click on the Autoscale button
your teacher.
and then print copies of the graph as directed by
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Activity 2
1. Transfer data from the computer to Chart 1, “Magnetic Field Strength.”
CHART 1
MAGNETIC FIELD STRENGTH
WINDS
(#)
MAGNETIC FIELD
(mT)
WINDS
(#)
0
12
3
15
6
18
9
21
MAGNETIC FIELD
(mT)
2. Sketch the graph created by LoggerPro. Pay close attention to the intervals as you sketch
your graph.
GRAPH 2
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Analysis
1. Describe the relationship between the number of wraps of wire in an electromagnet and the
strength of its magnetic field. Use specific data from the investigation to support your
response.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2. Read your graph and predict the magnetic field strength for 5 winds of wire and for 17 winds
of wire.
5 winds _______
17 winds _______
3. Explain the advantages and disadvantages of using technology to investigate
electromagnetism. Use specific information from the investigation to support your response.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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4. Write a conclusion to summarize the results of this investigation. In your conclusion, be sure
to include the following:
 The question you investigated
 Your hypothesis
 A summary of the results
 An explanation of the results using supporting information about energy
transformations
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Learning Log
Explain how you could use an electromagnet in a ROOM PROTECTOR to convert
electrical energy to mechanical energy.
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Student Resource Sheet EEM - 15
INVESTIGATION 2: ELECTROMAGNETS
You have already discovered how the number of wire wraps affects the strength of an
electromagnet. In this investigation, you and your team will design and conduct an investigation
in order to explore one of the other variables that s the strength of an electromagnet. You will
present your findings to your classmates by sharing your procedure and the results you obtained.
These presentations will help you design an electromagnet that can be used in your ROOM
PROTECTOR.
Objective
After completing this investigation, you should be able to
1. collect and analyze data in order to describe how one selected variable can affect the
strength of a magnetic field generated by an electromagnet.
Procedure
1. Record the following information for your investigation using the graphic organizer.
a.
b.
c.
d.
e.
The problem question your team will investigate
The independent variable
The dependent variable
Variables you need to control
Your hypothesis
Problem Question
Variables
Independent
Dependent
Controlled
Hypothesis
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2. Review the list of materials that has been provided by your teacher.
3. Design your investigation using the following information.
CRITERIA FOR A WELL-DESIGNED INVESTIGATION:
• only one variable is tested
• testing conditions such as time, temperature, and surfaces are controlled
• multiple trials are completed
• appropriate materials and equipment are selected
• clear, logical directions are included
4. Write the procedures to investigate your group’s problem question using the materials you
have been given. Be sure that your experimental procedure effectively controls all variables
that could affect the outcome of the investigation. It is not necessary to re-write the steps
needed to collect data using LoggerPro outlined in “Steps in Collecting Magnetic Field Data
with the LoggerPro.”
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
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Student Resource Sheet EEM - 15
STEPS IN COLLECTING MAGNETIC FIELD DATA WITH THE LOGGERPRO
A. Tape a Magnetic Field Sensor to the tabletop. The white side of the sensor (or white dot)
should face up and be parallel to the tabletop.
B. Plug the Magnetic Field Sensor into the computer interface. Set the switch to the LOW
x10 amplification setting.
C. Click
to zero the sensor.
D. Click on the Data Collection button
tool bar.
next to the Lab Pro button
in the
E. In the Mode window, select “Events with Entry.”
F. In the Column Name window, type the name of your independent variable.
G. In the units window, type the name of the unit of measurement you will use for your
independent variable. For some variables, you may need to leave this field blank.
H. Collect data for your first trial.
a. Click
.
b. Place the end of the core of the electromagnet perpendicular to the top of the
Magnetic Field Sensor at its very end, as you did in Investigation 1. When the
reading has stabilized, click
.
c. Type “1” in the edit box (for trial 1).
d. Press ENTER. The magnetic field strength value for your first trial is now saved.
I.
Collect data for your next trial.
J. When the reading has stabilized, click
.
K. Type “2” in the edit box for trial 2.
L. Press ENTER. The magnetic field strength value for trial 2 is now saved.
M. Repeat Step G for your remaining trials. Caution: The battery will become warm as it is
used. To keep it from getting hot, and to save energy, remove the wire from the top of
the battery immediately after
has been clicked.
14. When you have finished collecting data for your final trial, click
collection and then
to autoscale the graph.
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to end data
Student Resource Sheet EEM - 15
5. Design a data chart that you will use to record data collected in your investigation. Be sure
to include the following information in your chart.
a.
b.
c.
d.
e.
The independent variable
The dependent variable
Units of measurement
Title
Appropriate data
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6. Decide which type of graph you will use to display the data. If your independent variable is
a measurable quantity, you will use a line graph. If your independent variable is a material,
you will use a bar graph. When you set up LoggerPro, you will need to enter this information
using the following steps.
a. Double-click on the X in the Data Set after opening LoggerPro.
b. Click on the Column Definition tab and type the name of your independent
variable in the Name: text field.
Units Text Field
c. Add the unit of measurement in the Units: field if your independent variable is a
measurable quantity. Click on the Treat Column Cells as Text box if it is not
measurable.
d. Click DONE when you have finished.
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e. Double click on the graph in order to set up the type of graph you will use to
display the data. Type in an appropriate title in the Title: text field.
f. Click on the Connect Points box for a line graph or on the Bar Graph box if you
will use a bar graph to display data.
You are now ready to collect your data!
7. Conduct your investigation using LoggerPro.
8. Record the data collected on the data chart you constructed.
9. Save your data and graph according to your teacher’s instructions.
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Activity 3
10. Write a conclusion for your investigation that includes the following information.
□
□
□
□
The question you investigated
Your hypothesis
A summary of the results
An explanation of the results using supporting evidence
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Activity 4
11. Brainstorm with your group and organize a presentation for your classmates in order to share
the results of your investigation. Be sure that your presentation includes the following
information:
□
□
□
□
The question you investigated
A summary of your procedure and materials used
The data chart and graph constructed using LoggerPro
The conclusion to the investigation
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Analysis
1. Complete Chart 2, “Variables That Affect the Strength of an Electromagnet.”
CHART 2
VARIABLES THAT AFFECT THE STRENGTH OF AN ELECTROMAGNET
INDEPENDENT
VARIABLE TESTED
SUMMARY OF RESULTS
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IDEAS FOR THE
ELECTROMAGNET
YOU WILL DESIGN
Student Resource Sheet EEM - 15
Learning Log
Suppose you were going to use an electromagnet in a ROOM PROTECTOR to
move a magnetic object. Use information from the class presentations to design the
strongest electromagnet you can. You must limit the design to only the materials
tested by your classmates. List and justify the materials you selected. Include a
labeled diagram showing how the parts of your electromagnet would be assembled.
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