demonstrations:electromagnetic_shielding_with_faraday_cage

Electromagnetic Shielding with a Faraday Cage

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Electricity, Electromagnetic Spectrum and Waves

Alternative titles: Faraday's Cage

Summary

An AM/FM radio is placed inside a Faraday cage to demonstrate how the cage blocks electromagnetic waves, preventing the radio from receiving signals.

Procedure

  1. Turn on the AM/FM radio and tune it to a station with a clear signal.
  2. Place the radio inside the Faraday cage.
  3. Close or secure the cage completely.
  4. Observe that the radio signal weakens or disappears.
  5. Remove the radio from the cage to show the signal returning.

Electromagnetic Radiation Demo: Faraday Cage - Physics Demos:


📄 Faraday's Cage - Idaho State University: https://www.isu.edu/physics/outreach/physics-class-demos/electricity-and-magnetism/faradays-cage/

Variations

  • Try different devices such as a cell phone or walkie-talkie inside the cage.
  • Use cages of different materials (e.g., wire mesh, metal box) to compare effectiveness.
  • Test signal strength at different frequencies (AM vs FM).

Safety Precautions

  • Ensure the Faraday cage does not have sharp edges that could cause cuts.
  • Handle electronic devices carefully to avoid damage.
  • Do not connect the cage to a power source.

Questions to Consider

  • Why does the signal weaken or disappear when the radio is placed inside the cage? (The metal cage redistributes electric charges, blocking external electromagnetic fields from penetrating inside.)
  • Why might AM signals be blocked more effectively than FM signals? (AM has longer wavelengths that may be more easily blocked by certain cage sizes and mesh spacing.)
  • How is this principle applied in real-world technology? (Examples: shielding cables, microwave ovens, secure rooms against eavesdropping.)