Magnetic Fields with Iron Filings

This activity uses iron filings sprinkled over paper or a transparency placed on a magnet to reveal magnetic field patterns. The filings align themselves along invisible magnetic field lines, providing a visual representation of the field.

1. Place a sheet of paper or transparency over a bar magnet to prevent filings from sticking to it.
2. Trace the outline of the bar magnet and mark its north and south poles.
3. Lightly sprinkle iron filings evenly over the paper.
4. Gently tap the paper to help the filings align with the magnetic field lines.
5. Observe the pattern that forms, particularly the curves from north to south poles.
6. Record observations and compare with compass tracing patterns made earlier.
7. Discuss and write hypotheses explaining why the filings form the observed shapes.

Magnetic Fields – Observing Magnetic Force - Next Generation Science:

Plotting Magnetic Field Lines - QuantumBoffin:

📄 Iron Filings and Magnetic Field Lines - lasp.colorado.edu: https://lasp.colorado.edu/wp-content/uploads/2011/08/P1-2_3D_field.pdf

• Place two bar magnets side by side with opposite poles facing each other and observe how the fields combine.
• Place two bar magnets with like poles facing each other and observe the field repulsion pattern.
• Use horseshoe magnets to see how their fields differ from straight bar magnets.
• Demonstrate on an overhead projector using a transparency to show the whole class at once.

• Keep a sheet of paper or transparency between the magnet and the iron filings to prevent filings from sticking directly to the magnet.
• Handle iron filings carefully; they are messy and difficult to clean up if spilled.
• Keep filings away from eyes, mouth, and electronic devices.
• Wash hands thoroughly after handling iron filings.

• What do the iron filings reveal about the magnetic field? (They align along field lines showing the field’s shape and direction.)
• Why do the filings form curved lines between the poles of the magnet? (Magnetic field lines extend from the north pole to the south pole in curved paths.)
• How does the pattern compare to the earlier compass tracing activity? (They should match, since both reveal the same field lines.)
• Why do the filings act like tiny magnets? (Each filing becomes a temporary magnet when exposed to the bar magnet’s field and aligns along the field.)
• What happens when two magnets are placed with opposite poles facing each other? (The fields combine, showing strong attraction.)
• What happens when two magnets are placed with like poles facing each other? (The fields repel, and the filings show areas where lines bend away from each other.)