The Invisible Shield Stopping Electricity

A simple metal cage can block lightning and radio signals, even if it is full of holes. By acting as a shield for electromagnetic energy, it forces electricity to flow around the exterior instead of penetrating the inside.

You might think a solid wall is needed for protection, but a metal mesh works just as well because electricity prefers to travel along the outer surface of conductors. This is why you are safely protected inside a car during a thunderstorm or why elevators can kill your cell phone signal. Michael Faraday discovered this phenomenon in 1836, forever changing how we protect sensitive electronics from interference. It remains one of the most effective ways to create an electromagnetic void.