Physical Science 1422
Department of Physics and Geology
Magnetism
Equipment Needed
Magnaprobe
Magnetic Field Viewer
Magnetized Needle
Qty
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1
1
Equipment Needed
Magnet Kit
Rotating Support
Qty
1
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Background
Magnets are readily available today because we know how to make them. But magnets were once
quite scarce and were found only as rocks in nature, or natural magnets. Natural magnets, called
loadstones, were discovered as early as the sixth century BC in ancient Greece in the province of
Magnesia, from which magnetism derives its name. Loadstones could attract pieces of iron and other
loadstones.
Sometime around the first century BC, the Chinese learned to make artificial magnets by stroking
pieces of iron with natural magnets. It is believed that the Chinese were the first ones to create the compass
by hanging a piece of loadstone or a magnet from a string. Since the beginning of the seventeenth century
scientists suggested that the Earth acts as a huge magnet. The Earth’s magnetic field is the cause of
compasses ability to point north. Experiments have determined that the magnetic field of the earth extends
many hundreds of miles into space. The origin of the Earth’s magnetic field is not known. Figure 1
illustrates the magnetic field of the Earth and its direction. Note that the magnetic south of the Earth is
near the geographic North (N) Pole.
Figure 1.The magnetic field of the Earth.
In a compass we name the poles North and South Poles based on the magnets behavior in the presence
of the Earth’s magnetic field. Both in bar and horseshoe magnets, the magnetic poles are located at the
two ends. Just as in static electricity, two like poles will repel and opposites will attract.
All magnets have a magnetic field. Magnetic field lines can be traced using small iron filings placed
in the vicinity of a magnet.
Magnets can be created in many different ways. An unmagnetized piece of iron can be magnetized by
stroking it with a magnet. Also, if a piece of unmagnetized iron is placed near a strong permanent magnet,
the piece of iron eventually becomes magnetized. Naturally occurring magnetic materials, such as
magnetite, achieve their magnetism in this manner because they have been subjected to Earth’s magnetic
field over very long periods of time. Another method to create magnetism is using electric currents. A
magnet made by a changing current in wires is called an electromagnet.
SAFETY REMINDER
•
Do not drop the magnets, and make sure that like poles on the
magnets are not left touching each other.
•
Follow the directions for using the equipment.
For You To Do
In this laboratory activity, you will study the properties of various magnets.
PART I: Equipment Setup and Data Collection
I. Magnetic Materials
1. Slowly move a piece of loadstone (the rock in magnet kit) near the magnaprobe. Move the
magnaprobe around the loadstone without touching the rock and record your observations in the
lab report section.
2. Bring the Horseshoe magnet near each metal sample and determine whether it is a magnetic or non
magnetic material. Record your observations in the lab report section.
II. Magnetic Poles
A. Properties of magnetic poles
1. Place a bar magnet on the rotating support as shown in the figure.
2. Slowly bring the North pole of another bar magnet close to the
North pole of the bar magnet on the rotating support. Record your
observations in the lab report section.
3. Slowly bring a North Pole near the South Pole and record your
observations in the lab report section.
III. Compass
1. Move all magnets far away from the stand and place the magnetized needle on the stand.
2. Slightly push the needle and wait until the needle settles down. The blue side of the needle is a
magnetic North Pole. Notice that the blue side of the needle points geographic North direction.
3. Push the needle to rotate 180◦ and let it go. After the needle settles down, record your observations
in the lab report section.
IV. Magnetic Field Lines
A. Compass
1. Place a bar magnet on top of a sheet of white paper.
2. Hold a magnetic field viewer with both hands and slowly tilt the viewer. Notice that a small glass
bar is moving inside the viewer. Spread iron fillings uniformly by moving the glass bar back and
forth.
3. Flip the viewer and quickly place it on top of the magnet.
4. Wait a few minutes and observe the magnetic field lines.
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5. Sketch the field lines as continuous lines in the figure in the lab report section. Indicate the
direction of magnetic fields with arrows.
B. Two Bar Magnets
1. Arrange two bar magnets pointing like poles and 3 cm apart on top of a sheet of paper.
2. Spread iron fillings uniformly inside the magnetic field viewer.
3. Flip the viewer and quickly place it on top of magnets.
4. Wait a few minutes and observe the magnetic field lines.
5. Sketch the field lines as continuous lines in the figure in the lab report section and indicate the
direction of magnetic fields with arrows.
6. Rearrange magnets to point to opposite poles and sketch the field lines in the figure in the lab
report section.
C. A Horseshoe Magnet
1. Place a horseshoe magnet on top of a sheet of paper.
2. Spread iron fillings uniformly inside the magnetic field viewer.
3. Flip the viewer and quickly place it on top of the magnet.
4. Wait a few minutes and observe the magnetic field lines.
5. Sketch the field lines and indicate the direction of magnetic fields as arrows in the figure in the lab
report section.
D. Round Magnet
1. Place a round magnet on top of a sheet of white paper.
2. Spread iron fillings uniformly inside the magnetic field viewer.
3. Flip the viewer and quickly place it on top of the magnet.
4. Wait a few minutes and observe the magnetic field lines.
5. Sketch the field lines as continuous lines in figure in the lab report section. Indicate the direction
of magnetic fields with arrows.
E. Two Doughnut shaped Magnets
1. Arrange two doughnut shaped magnets with like poles pointing 3 cm apart on top of a sheet of
paper. (place the two magnets near each other if they are not pushing apart, then turn one of them
over)
2. Spread iron fillings uniformly inside the magnetic field viewer.
3. Flip the viewer and quickly place it on top of magnets.
4. Wait a few minutes and observe the magnetic field lines.
5. Sketch the field lines as continuous lines in the figure in the lab report section and indicate the
direction of magnetic fields with arrows.
6. Rearrange magnets pointing opposite poles (place the two magnets near each other, if they are
pushing apart, then turn one of them over) and sketch the field lines in the figure in the lab report
section.
Record your results in the Lab Report section.
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