Download 41B Magnetic Fields of Force - Merrillville Community School

41B
LA
O
RY
Magnetic Fields of Force
T
BO RA
T
he forces most responsible for plate motion and erosion are
directly applied mechanical forces. Some of the other forces
affecting the Earth act at a distance, such as gravitational and
magnetic fields. Gravity is a force that affects all materials and
causes them to be attracted to each other. Although magnetic fields
only affect only some materials, they can create both attractive and
repulsive forces that can be easily detected, observed, and measured.
Common materials on earth that can be magnetic are made from the
metallic elements iron, nickel, and cobalt. Magnetism is a force that
arises from an invisible force field that surrounds certain materials.
Many natural phenomena, such as gravity, electricity, and magnetism, are associated with invisible fields of force. The Earth’s gravitational force field is what causes everything close to Earth to fall, or be
pulled, towards the center of the Earth. Electric fields can cause your
socks to stick together after they’ve been in the dryer.
How do we know there is such a thing as an invisible magnetic
field?
MATERIALS
For each group of students
10
1
30-mL cup with 30 iron washers
2
bar magnets
1
15-cm ruler
1
magnetic field visualizer
Magnetic Fields of Force • Activity 41B
PROCEDURE
Part A: Magnetic Interactions
1. Use your fingers to slowly remove one washer from the cup.
Observe what happens to the other washers in the cup. Record your
observations and return the washer to the cup.
2. Hold a magnet by its red end and dip the unmarked end into the
cup with washers. Lift the magnet up and record your observations.
3. Remove the washers from the magnet and return them to the cup.
4. Holding the magnet by its red end, and making sure that only one
washer touches the magnet, lift up as many washers as you can.
5. Count and record the number of washers the unmarked end could
lift and return the washers to the cup.
6. Now hold the magnet by the unmarked end and repeat Steps 2 - 5
using the red end to lift the washers.
7. Construct a table similar to the one below.
End of 1 facing End of 2
Distance and Effect Observed
8. Lay your ruler on the tabletop and place 2 magnets along the edge
of the ruler as shown in the diagram below. Use the 1st row of the
table you just constructed to record which end of magnet 1 is facing which end of magnet 2.
Magnet 1
Magnet 2
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Activity 41B • Magnetic Fields of Force
9. Slowly push magnet 1 towards magnet 2 until you observe an
interaction between the magnetic fields of the two magnets.
10. Repeat Steps 8 and 9 several times and use the 1st row of your
table to describe the interaction and record the distance between
the magnets when the interaction occurs.
11. Repeat Steps 8 -10 but this time, arrange the two magnets so that
different ends are facing each other. Record your arrangement
and observations in the 2nd row of your table.
12. Repeat Steps 8 -10 using an arrangement of the two magnets that
is different from either of your previous arrangements. Record
your arrangement and observations in the 3rd row of your table.
Part B: Magnetic Fields
13. Place one magnet on the tabletop and place the magnetic field
visualizer directly above, but not quite touching, the magnet.
Gently shake the magnetic field visualizer so that the iron filings
spread out evenly. Sketch the appearance of the filings.
ANALYSIS
1. Using evidence from this activity, describe the similarities and differences between a north magnetic pole and a south magnetic
pole.
2. Describe some observations that indicate the presence of an invisible force field surrounding a magnet.
3. Compare and contrast the basic shape of the magnetic field that
exists between nearby unlike magnetic poles (north and south)
and nearby like magnetic poles (north and north or south and
south).
4. Using evidence from this activity, describe a magnet as accurately
as you can
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