Electromagnetic Induction
012-11000 r1.04
Electromagnetic Induction
Introduction
Journals and Snapshots
The Snapshot button is used to capture the
screen.
The Journal is where snapshots are stored
and viewed.
The Share button is used to export
or print your journal to turn in your
work.
Each page of this lab that
contains the symbol
should be inserted into your
journal. After completing a
lab page with the snapshot
symbol, tap
(in the upper
right corner) to insert the
page into your journal.
Note: You may want to take a
snapshot of the first page of
this lab as a cover page for
your journal.
Electromagnetic Induction
Lab Challenge
You can send electricity through a
conducting wire to make a magnetic
field. Is the reverse possible? Can
you use a magnet and a conducting
wire to make electricity?
Electromagnetic Induction
Background
Michael Faraday (1791 - 1867) discovered a
relationship between a changing magnetic flux Φ,
and the potential within a conductor ε:
Known as Faraday's Law, this relationship is defined by two key elements, the
number of turns in a coil N, and the change in magnetic flux Φ. Magnetic flux is
related to the strength of the magnetic field, the area enclosed by the wire loop
and the angle between them. Because of the geometry of our experimental setup,
we can say that the flux is proportional to the strength of the magnetic field.
Electromagnetic Induction
Safety
Be careful with magnets.
Strong magnets can disrupt
electronic devices and
severely pinch any skin that
comes between them.
Electromagnetic Induction
Materials and Equipment
Collect all of these materials before
beginning the lab.
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Voltage Probe
3 Magnets of different strength
200 turn coil
400 turn coil
800 turn coil
Lab Stand (not shown)
Three fingered clamp
No Bounce pad (optional)
Paper, tape and a pen
Electromagnetic Induction
Sequencing Challenge
A. Connect the
Voltage Probe to the
SPARK Science
Learning System.
B. Drop the magnet
through the coil,
then stop data
collection.
Hint: This step is
used twice.
C. Compare the
Voltage produced by
the 200 turn coil to
that produced by
the 400 turn coil on
the graph.
D. Remove the 200
turn coil and replace
it with the 400 turn
coil.
The steps to the left are part
of the procedure for this lab
activity. They are not in the
right order. Determine the
correct sequence of the
steps, then take a snapshot
of this page.
Electromagnetic Induction
Part 1 - As the Coil Turns
In the first part of this lab, we determine if passing
a magnet through a coil of wire gives rise to a
voltage (or electromotive force), and secondly,
whether the number of turns in the coil N has any
effect on the amount of voltage as predicted in
Faraday's equation.
Note: For the best comparison, always be sure to use the
same orientation of the magnet when dropping it through
the coil.
Electromagnetic Induction
Prediction
Try to predict the shape of
the Voltage versus Time
curve using the Prediction
Tool*, then take a snapshot
of this page.
*To Draw a Prediction:
1. Tap
to open the tool
palette.
2. Tap
then use your finger
to draw your prediction.
3. Tap
when finished.
4. If you make a mistake, tap
to clear your prediction.
Electromagnetic Induction
Setup
1. Mount the 200 turn coil to the lab stand
using the three finger clamp,
approximately 40 cm above the lab table.
2. Connect the voltage probe to the coil.
3. Connect the voltage probe to your SPARK
Science Learning System.
4. If you are using a pad place it below the
coil.
Electromagnetic Induction
Collect Data
1. Hold the magnet just
above the coil opening.
2. Tap
to start data
collection.
3. Drop the magnet through
the coil then quickly tap
to stop data collection
(~1 sec).
4. Switch coils.
5. Repeat steps 1 through 4
for each coil, dropping the
magnet from the same
height each time.
Electromagnetic Induction
Analysis
1. Adjust the scale of the
graph to fit data for all
three runs, then indicate in
the text box below which
run corresponds to which #
turn coil.
Electromagnetic Induction
Analysis
2. Briefly describe one of
the major differences
between runs in the text
box below.
Electromagnetic Induction
Electromagnetic Induction
Analysis
3. Describe the relationship between the number of turns in the
coils and the peak voltages you observed. Take a snapshot of
the page after entering your response.
Electromagnetic Induction
Part 2 - More Magnet
The second part of Faraday's equation refers
to the amount of change in magnetic flux.
From our observations of magnets, different
types of material produce different
strengths of magnetic field. Try at least two
magnets of different strengths to see if the
strength of the magnet makes a difference.
Use only one of the coils and drop the
magnets from the same height each time.
Electromagnetic Induction
Part 2 - More Magnet
Before proceeding to data collection, first
delete* all of the data currently in this
SPARKlab. Make certain you have already
snapshot the data on pages 12 and 13 before
deleting.
*To Delete all Data Runs:
1. Tap
to open the Experiment Tools screen.
2. Tap MANAGE RUNS.
3. Tap DELETE ALL RUNS.
4. When asked to confirm deletion, tap YES.
5. Tap OK to return to the SPARKlab.
Electromagnetic Induction
Collect Data
1. Hold the magnet just
above the coil opening.
2. Tap
to start data
collection.
3. Drop the magnet through
the coil then quickly tap
to stop data collection
(~1 sec).
4. Switch magnets.
5. Repeat steps 1 through 4
for each magnet, dropping
the magnet from the same
height each time.
Electromagnetic Induction
Analysis
4. Adjust the scale of the graph
to fit data for the last three
runs, then indicate in the
text box below which run
corresponds to which
magnet.
Electromagnetic Induction
Analysis
5. Briefly describe one of the
major differences between
the last three runs in the
text box below.
Electromagnetic Induction
Analysis
6. Describe the relationship between the strength of magnet used
and the peak voltages you observed. Take a snapshot of the page
after entering your response.
Electromagnetic Induction
Part 3 - The Faster the Flux
If the strength of the magnet affects the change
in flux, how about the speed at which the
magnet passes through the coil? Studies of
acceleration show that the farther an object falls
in a gravitational field, the faster it travels. If the
magnet passes through the coil faster, it is
reasonable that the magnetic flux in the coil is
changing faster. Use one of your coils to find out.
Electromagnetic Induction
Part 3 - The Faster the Flux
Before proceeding to data collection, first delete*
all of the data currently in this SPARKlab. Make
certain you have already snapshot the data on
pages 18 and 19 before deleting.
*To Delete all Data Runs:
1. Tap
to open the Experiment Tools screen.
2. Tap MANAGE RUNS.
3. Tap DELETE ALL RUNS.
4. When asked to confirm deletion, tap YES.
5. Tap OK to return to the SPARKlab.
Electromagnetic Induction
Setup
Roll up a piece of paper into a tube
and tape it securely. The tube should
be wide enough to allow your
magnet to pass through freely, but
narrow enough to fit inside the coil.
You will mark four positions on the
tube. With the tube in place, you
will drop the magnet from the
opening of the tube, then slide the
tube through the coil to each mark,
dropping the magnet from the tube
opening each time.
Electromagnetic Induction
Collect Data
1. Hold the magnet just
above the tube opening.
2. Tap
to start data
collection.
3. Drop the magnet through
the tube then quickly tap
to stop data collection
(~1 sec).
4. Adjust the tube height.
5. Repeat steps 1 through 4
for each height, dropping
the magnet from the tube
opening each time.
Electromagnetic Induction
Analysis
7. Adjust the scale of the graph
to fit data for the last four
runs, then indicate in the
text box below which run
corresponds to which
height.
Electromagnetic Induction
Analysis
8. Briefly describe one of the
major differences between
the last four runs in the
text box below.
Electromagnetic Induction
Analysis
9. In the text box below describe the relationship between the height
at which the magnet fell above the coil and the peak voltages you
observed. Then take a snapshot of this page.
Electromagnetic Induction
Analysis
10. How does your prediction compare to the actual voltage versus time graph?
Answer below, then take a snapshot of this page.
Electromagnetic Induction
Synthesis
1. Based on your observations in this lab, describe the characteristics of an electric coil
generator that you would optimize to get the most electromotive force out. Answer
below, then take a snapshot of the page.
Electromagnetic Induction
Synthesis
2. You may have noticed that the second peak of the voltage curve is always in the
opposite direction of the first peak, but you may not have noticed that it is also a
slightly higher peak. Can you describe why that might be?
Electromagnetic Induction
Multiple Choice Question
1. Dropping a magnet through a coil is a form of
energy transformation. What kind of
transformation is it?
a) Thermal energy is transformed into electrical
energy.
b) Mechanical energy is transformed into thermal
energy.
c) Kinetic energy is being transformed into
electrical energy.
d) Electrical energy is being transformed into
thermal energy.
Make your selection below
then take a snapshot of this
page.
Electromagnetic Induction
Multiple Choice Question
2. If a generator with a 200 turn coil produced 120 V
of EMF, how much would it produce if it was
upgraded to an 800 turn coil?
a) 40 V
b) 480 V
c) 220 V
d) There is not enough information to draw a
conclusion.
Make your selection below
then take a snapshot of this
page.
Electromagnetic Induction
Multiple Choice Question
3. The equation for Faraday's Law includes a negative
sign on one side. What does it represent?
a) Magnetism is an inherently negative force.
b) Opposites attract.
c) The EMF generated seeks to reinforce the
change in magnetic field.
d) The EMF generated seeks to oppose the change
in magnetic field.
Make your selection below
then take a snapshot of this
page.
Electromagnetic Induction
Congratulations!
You have completed the lab.
Please remember to follow your teacher's instructions for cleaning-up and submitting
your lab.
Electromagnetic Induction
References
ALL IMAGES WERE TAKEN FROM PASCO DOCUMENTATION, PUBLIC DOMAIN CLIP ART, OR WIKIMEDIA
FOUNDATION COMMONS:
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http://commons.wikimedia.org/wiki/File:Michael_Faraday_-_Project_Gutenberg_eText_13103.jpg
http://commons.wikimedia.org/wiki/File:SGR_1806-20_108536main_NeutronStar-Print1.jpg
http://commons.wikimedia.org/wiki/File:D-W015_Warnung_vor_Absturzgefahr_ty.svg
http://commons.wikimedia.org/wiki/File:Dipole_field.jpg
http://commons.wikimedia.org/wiki/File:DIN_4844-2_Warnung_vor_magnetischem_Feld_D-W013.svg
http://commons.wikimedia.org/wiki/File:ForceLorentz.svg
http://commons.wikimedia.org/wiki/File:NSRW_Direct_Connected_Dynamo_and_Engine.png
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