How do you block out electromagnetic fields?

• A. Faraday cage
• B. Transformer
• C. Inductor
• D. Capacitor

Answer: (A)

Blocking electromagnetic fields is achieved through shielding with a conductive enclosure. A Faraday cage does this by allowing external fields to induce charges on the surface that rearrange themselves to cancel the field inside the enclosure. In practice, a continuous metal shell around the space or device protects it from static or slowly varying fields, and for higher frequencies the enclosure must be thick compared to the skin depth and free of large gaps, seams, or holes (which would let fields leak in). Grounding can help furtherreduce interference, but the key idea is the conductive barrier that redirects and neutralizes the incoming field.

The other components aren’t designed for shielding. A transformer is built to transfer energy between circuits via magnetic coupling and a core, not to block external fields. An inductor stores energy in a magnetic field and can interact with nearby fields, and a capacitor stores energy in an electric field; neither serves as a protective barrier against external electromagnetic fields.