Magnets
What causes magnetic forces?
Exploration Phase
Lab Activity
Look at all the pieces in your kit. Pick out two small bar magnets and try to
bring them near each other. Also, bring them near the other objects in your
kit (the wire, screw, paper clip, etc.). Observe and record how they push
and pull. These pushes and pulls are attractive and repulsive forces.
Describe your observations below.
Consider the statement: “Opposites attract and likes repel” Does this
statement agree or disagree with your observations? Explain.
Lab Activity
Now go back to your kit. Pick out the the compass. Lay it flat on your table far
from any magnets. Observe which is the north end of the compass, meaning the
one which points to the north.
Briefly record which end of the magnet is the north end (red or black) and
what you had to do to determine this.
Lab Activity
Now go back to your kit. Pick out the small bar magnet and the compass. Lay
the bar magnet on your table and place the compass at many different points
around the magnet. In the diagram below, label N and S on the drawing of the
magnet, and draw an arrow pointing the way the North point of the compass
points in all the different places in the drawing above.
Then, pick up and drop the compass in all the different places. Observe how
quickly its pointer vibrates and returns to its reading. This is an indicator of the
strength of the field. Record the relative strength of the field in your diagram
below.
Briefly describe the direction the compass points and the strength of the
field observed when placed near the magnet in words.
Lab Activity
Pick out the long piece of wire and coil it around the nail. Pick out the
battery, and connect the ends of the wire to the ends of the battery. Lay
the coil of wire around the nail on your table and place the compass at
many different points around the coil. Make a drawing of the magnet and
compass that shows the way the compass points in all the different places
by drawing an arrow in the direction the north end of the compass points.
If the wire gets hot, disconnect, let it cool, and then connect again.
How does the compass deflect due to the current in the coil around the
nail? How does its deflection compare to the deflection due to a bar
magnet?
How does the magnetic field you observe from this electromagnet compare
to the field of the earth?
Make a hypothesis about the source of the earth’s magnetic field below.
Concept Introduction Phase
Please discuss the results of the activity with your lab partners. Summarize the results in
your own words below.
Now, describe the results of the activity using the following words: magnetism,
permanent magnet, temporary magnet, north, south, attract, repel, electromagnet.
Now we will discuss with the group. Make some notes below.
Application Phase
Lab Activity:
Place your magnet on the table, and place the baggy of iron filings on top.
Shake it a bit, and observe the pattern.
Describe the pattern below. What does this pattern tell us about the field?
Lab Activity:
Now pick out one of the bar magnets, the piece of masking tape, and the
piece of string. Hang the bar magnet from the string and attach the
masking tape over the string where it passes around the magnet. This will
help it hold steady in a horizontal position. Now hold the string, allowing
the magnet to dangle. (You may need to just hold the string and walk away
from where your classmates are working to get sufficiently far from their
magnets.)
In which direction does the north end of the hanging magnet face? Why?
How does what you have created compare with a compass?
To which geographic pole of the earth does the north pole of the magnet
point?
What type of magnetic pole is the North geographic pole of the earth? What
type of magnetic pole is the South geographic pole of the earth?
Terms
Compass, Magnet, Magnetic field, Permanent magnet, North, South, Attract,
Repel, Magnetic force, electrical current, earth, and any other terms.