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Mighty Magnets?
Will heating a magnet increase the strength of
the magnet?
Christy L. Moorman
September 9, 2010
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Abstract
Magnets are used in our every day lives. We have
become dependent their use in our society. A test was
conducted to find out the effect that heating a magnet would
have on the magnet’s strength. A magnet’s strength was
recorded at room temperature and then compared to its
strength after being heated. Results indicated that a magnet’s
strength does increase as the magnet it heated.
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Table of Contents
Abstract …………………………………………..….4
Statement of Purpose……………………………..…..6
Hypothesis……………………………………….…...7
Research………………………………………………8
Procedures……………………………………………12
Materials …………………………………….……….14
Results ……………………………………………….15
Conclusion ……………………………………………17
Bibliography ………………………………………….18
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Statement of Purpose
The purpose of this research is to determine if heating a
magnet will increase the strength of the magnet.
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Hypothesis
If the temperature of a magnet is increased, then the magnet
will be able to pick up more paperclips than the same magnet at
room temperature.
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Research
First discovered in Greece and China thousands of years ago
in a rock called lodestone, magnetic material has continued to be of
interest to scientists, inventors, and people around the world. A
magnet is an object that is surrounded by a magnetic field. The
magnetic field is the invisible force of the magnet that can be felt.
This force allows magnets to attract objects which contain iron,
nickel, steel, and some other materials.
Over time, people have learned more about how magnets
work. It was discovered that magnets have a north pole and a south
pole. It is at these poles that the magnet’s strength is the strongest.
They also found that two unlike poles will attract each other and
two like poles will repel or push away. One amazing discovery
was that the Earth is actually a natural magnet. This led to the
invention of the first compass. Other natural magnets include stars,
some planets, and the Sun.
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There are different shapes of magnets. Bar magnets, Ushaped magnets called horseshoe magnets, and round, flat disk
magnets. A magnet cut in half will result in two magnets that each
have a north and a south pole.
Magnets can transfer their magnetism to other materials. For
example, if a bar magnet is used to pick up a paper clip, the paper
clip can become magnetized and pick up additional paper clips.
This would make the paper clip a temporary magnet. When
attracted metal becomes magnetized it is called magnetization.
The use of magnets has become a part of our every day lives.
Magnets are found in our cars, televisions, and computers. Even
your doorbell uses magnets. Sound devices such as telephones and
speakers for stereo systems, radios, and computers contain
magnets. They are also used in power plants that provide the
electricity needed to operate many of the devices we use daily.
Electric motors which supply power to cars, toys, washing
machines, and dryers rely on magnets for operation. Physicians
rely on magnets to help diagnose and treat medical problems by
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using an x-ray machine called an MRI. There are even some
animals which have small magnets in their bodies which may help
them when migrating. Recently, Maglev trains have been
developed that work by putting a magnetic train on a magnetic
track. Like poles of the magnets cause the train to levitate or float
above the track.
Different magnets have different strengths. Scientists
measure the strength of magnetic fields in units called gauss and
tesla. A magnet’s strength can also be simply measured by
recording the number of paper clips a magnet can attract. In an
attempt to discover if temperature has an effect on a magnet’s
strength, the independent variable of temperature will be tested.
Control variables include the magnet used, the size and type of
paperclips, how long temperature is recorded, and how long the
magnet is heated. The dependent variable is the number of paper
clips that the magnet will attract or pick up. With so much of our
daily activities dependent on magnets, it is important that we
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understand any factors or variables that could affect the strength of
a magnet.
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Procedures
1. Assemble materials.
2. Make a pile of 45 small paper clips.
3. Measure the temperature of the magnet at room temperature by
laying the bulb of the thermometer against the surface of the
magnet and leaving it there for 2 minutes.
4. Record the temperature.
5. Use the magnet to pick up paper clips from the pile. Lift the
magnet into the air and hold it there. After 10 seconds, count and
record the number of clips that stayed connected to the magnet.
6. Put these magnetized clips away. They will not be used again.
7. Repeat steps 2-6 two additional times for a total of three trials.
8. Plug in the hot plate and turn it on to medium heat. Let it heat
for five minutes or until the indicator light shows that the plate is
heated.
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9. Place a sheet of aluminum foil on the hot plate to keep any paint
on the magnet from transferring to the plate. Place the same
magnet onto the hot plate. Leave it there for three minutes.
10. Make a new pile of 45 small paper clips.
11. Using wooden tongs pick up the magnet and lay it on the hot
pad. DO NOT TOUCH THE HOT MAGNET.
12. Measure and record the temperature of the magnet as described
in steps 3 and 4.
13. Using the tongs, pick up the magnet and use it to pick up paper
clips from the pile. DO NOT TOUCH THE HOT MAGNET. Lift
the magnet into the air and hold it there. After 10 seconds, count
and record the number of clips that stayed connected to the
magnet.
14. Put these magnetized clips away. They will not be used again.
15. Repeat steps 9-14 two additional times for a total of three trials.
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Materials








1 all-metal bar magnet
150+ small metal paper clips
1 metal dry bulb thermometer
1 hot plate with low, medium, and high settings marked
1 hot pad
1 pair of wooden tongs or chop sticks
1 stop watch
1 12-inch sheet of aluminum foil
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Results
When tested, a magnet at an average room temperature of
26ºC attracted an average of 39 paper clips. A magnet heated to an
average temperature of 71ºC attracted an average of 44 paper clips.
This data supports the hypothesis that a magnet’s strength
increases when it’s temperature increases.
Paper Clips Attracted at Room Temperature
Temperature
of Magnet
Number of
Paperclips
Trial 1
26ºC
Trial 2
26ºC
Trial 3
26ºC
Average
26ºC
36
43
38
39
Paper Clips Attracted at Heated Temperature
Temperature
of Magnet
Number of
Paperclips
Trial 1
57ºC
Trial 2
71ºC
Trial 3
85ºC
Average
71ºC
43
45
45
44
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Conclusion
Results of this experiment support the hypothesis that a
magnet’s strength increases when the magnet is heated.
Therefore, the hypothesis can be accepted. However, there is
one possible source of error in this experiment.
Measurements of temperature at room temperature and
heated temperature were taken using two different
thermometers due to availability of one thermometer that
would measure a high enough range of temperatures. It is
assumed that the two thermometers used are accurate;
therefore, there should no strong effect on the data collected.
More research could be done to further support the
hypothesis by cooling or freezing a magnet to determine if
the magnet’s strength decreases.
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Bibliography
Bonsor, Kevin. "How Maglev Trains Work" 13 October 2000.
HowStuffWorks.com. Retrieved August 26, 2010 from
http://science.howstuffworks.com/transport/enginesequipment/maglev-train.htm>
Eden, Guinevere. "Magnetic resonance imaging (MRI)." World
Book Student. World Book 2010. Retrived August 21, 2010,
from
http://www.worldbookonline.com/student/article?id=ar33837
0&st=magnets+and+mri.
Greenberg, D. (Ed.). Magnetism. New York, NY: Macmillan
McGraw-Hill.
Schwartz, Brian B., and Richard B. Frankel. "Magnetism." World
Book Student. World Book, 2010. Retrieved August, 21,
2010, from
http://www.worldbookonline.com/student/article?id=ar33841
0&st=magnets
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