---
category: Scientific Theory & Technology
created: 2025-07-23
description: A Faraday cage is an enclosure used to block electromagnetic fields.
start: 1836
summary: A Faraday cage is an electromagnetic shielding enclosure invented by Michael
  Faraday in 1836, used in parapsychology research to test whether psychic phenomena
  could be blocked by shielding subjects from external electromagnetic signals.
tags:
- concept
- technology
- physics
title: Faraday Cage
updated: 2025-07-23
---

A [Faraday Cage](/concepts/faraday-cage/) is an enclosure used to block electromagnetic fields. It is named after the English scientist Michael Faraday, who invented it in 1836. A Faraday cage's operation depends on the fact that an external electrical field causes the electric charges within the cage's conducting material to be distributed such that they cancel the field's effect in the cage's interior.[^1]

In the context of psychic research, Faraday cages were used to test the theory that [ESP](/concepts/extrasensory-perception/) is a form of electromagnetic radiation. [Andrija Puharich](/people/andrija-puharich/) and Jack Hammond built a Faraday cage at the [Round Table Foundation](/organizations/round-table-foundation/) to test psychics like [Eileen Garrett](/people/eileen-garrett/). The fact that Garrett's ESP scores were reportedly higher inside the cage suggested that some form of electromagnetic shielding might enhance psychic functioning. The only electromagnetic waves that can penetrate a Faraday cage are extremely low frequency (ELF) waves, which led to further research into the connection between ELF waves and ESP.[^1]

---

[^1]: Jacobsen, Annie. *Phenomena: The Secret History of the U.S. Government's Investigations into Extrasensory Perception and Psychokinesis*. Little, Brown and Company, 2017.