The world relies on electromagnetic waves for communications: Wi-Fi, Bluetooth, 5G, even radio waves. But suppose you want to prevent a device from communicating—or interfering—with the rest of the world. You can’t block EM waves, but you can cancel them by surrounding the device with an electrically conducting material. We call this a Faraday cage, and here’s how it works.
An electric charge (like a proton) creates an electric field in the region around it. This field points away from positive charges and decreases in strength as it gets farther away from the charge. Here’s a visualization of the electric field, showing a positive charge (the red sphere) along with
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