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