demonstrations:magnetic_shielding

Magnetic Shielding

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★★☆ Some safety precautions required to perform safely

Categories: Materials, Magnetism

Alternative titles: Blocking Magnetic Fields

Summary

This demonstration explores how different materials affect magnetic attraction. By placing objects between a magnet and a paper clip, you can observe which materials allow magnetic fields to pass through and which ones block or redirect them. It illustrates the concept of magnetic shielding and the behavior of magnetic field lines in various materials.

Procedure

  1. See links for below for experiment set up.
  2. Insert a plastic ruler between the magnet and the paper clip. Note whether the magnetic attraction remains.
  3. Repeat the test with a steel ruler and steel bookend, observing any decrease in attraction or shielding effect.
  4. Test different coins (copper, nickel, or mixed alloys) by placing them between the magnet and the paper clip.
  5. Compare which materials reduce or block the magnetic force and which do not.
  6. Discuss the differences between ferritic (magnetic) and austenitic (non-magnetic) steel.

Magnetic Shielding Demonstrations - Physics Lens:


📄 Magnetic Shielding - Physics Lens: https://www.physicslens.com/video-on-magnetic-shielding/

Variations

  • Try varying the thickness of the magnetic shielding material to see how it affects the result.
  • Use different types of magnets (e.g., bar magnet, neodymium disc) to compare field strength.
  • Test other metals such as aluminum, brass, or zinc to confirm they do not shield magnetic fields.
  • Use iron sheets of different shapes to visualize how magnetic field direction changes.

Safety Precautions

  • Handle strong magnets with care—they can pinch fingers or attract metal objects suddenly.
  • Keep magnets away from electronics, credit cards, and magnetic storage devices.
  • Avoid using brittle materials or sharp-edged metal objects.
  • Supervise younger students closely when handling small objects like coins or paper clips.

Questions to Consider

  • Which materials blocked the magnet’s attraction to the paper clip? (Magnetic materials such as ferritic steel.)
  • Why do some steels act as magnetic shields while others do not? (Ferritic steel contains iron atoms aligned magnetically; austenitic steel’s crystal structure prevents this.)
  • Why did the plastic ruler have no effect on the magnetic field? (Non-magnetic materials do not interact with magnetic field lines.)
  • How does a magnetic shield redirect field lines? (It provides a low-resistance path for magnetic fields, drawing lines through itself instead of letting them pass through the air.)
  • Where is magnetic shielding used in real life? (In electronic devices, MRI rooms, and sensitive instruments to prevent interference.)