Producing a Dipole Field Line

Activity: Producing a Dipole Field Line

sheet of plastic, bar magnets, iron filings, overhead projector (Optional)

This activity can be done as a laboratory investigation or as a teacher demonstration. The investigation will show a dipole field line.

This activity could be done in groups or as a demonstration using the overhead projector. This would depend on the amount of materials you have. If you choose to do the activity as a demonstration, follow the steps for the activity, but do the activity on the overhead projector so all students can see it.
Pass out the materials to the students.
Place a sheet of plastic over the entire bar magnet.
Sprinkle iron filings over the covered magnet.
Gently shake the sheet of plastic back and forth so the dipole field line is visible.
Draw the pattern of lines of force that is observed.
Discuss student observations by asking the following questions or statements:
- What were your observations?
- From your observations, how does the Earth act as a magnet?
- From your observations, describe the Earth's magnetic field.
- Make a prediction of how the lines of force would change if a second magnet was placed under the sheet of plastic.
Have students use a second magnet to see if their predictions were correct.
As the lab questions are being discussed and if this activity was used as a lab, you may want to use the overhead projector to show students what they should of seen when they did the experiment.

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Contact Karen Krupinsky (kgurley@gsfc.nasa.gov) or
Tammy Seergae (tseergae@umd.edu) for further information.