Faraday cage facts for kids

A common type of Faraday cage: it prevents machines inside from causing radio interference outside

A girl inside is protected from electric arcs outside

A Faraday cage is like a special box, room, or even a bag made of metal or a material that conducts electricity. It's designed to block electric fields and radio waves. This amazing invention is named after the English scientist Michael Faraday, who created it in 1836.

Faraday cages are very useful. They can protect sensitive electronic equipment from outside radio signals. They also stop radio waves from devices inside the cage from bothering other equipment nearby.

How a Faraday Cage Blocks Electricity

Imagine an electric field trying to get inside the cage. The cage's special material has tiny electric charges. These charges quickly move around and rearrange themselves. They create an opposite electric field inside the cage. This new field cancels out the outside field. This makes the inside of the cage safe and calm. No electric field can get through to the inside.

What Faraday Cages Are Used For

Faraday cages have many important uses. They protect delicate electronics from strong radio signals. For example, they can shield medical equipment like MRI machines. This stops outside signals from interfering with their work.

They also protect people and equipment from actual electric currents. This includes things like lightning strikes or static electricity shocks. If lightning hits a car, the metal body acts like a Faraday cage. The electricity travels around the outside of the car. It keeps the people inside safe.

Some Faraday cages are used to contain devices that produce radio waves. This stops their signals from interfering with other nearby electronics. For instance, a radio transmitter might be placed inside one. This prevents its powerful signals from causing problems.

Images for kids

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  EMI shielding around an MRI machine room

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  Faraday bags are a type of Faraday cage made of flexible metallic fabric. They are typically used to block remote wiping or alteration of wireless devices recovered in criminal investigations, but may also be used by the general public to protect against data theft or to enhance digital privacy.

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  Animation showing how a Faraday cage (box) works. When an external electrical field (arrows) is applied, the electrons (little balls) in the metal move to the left side of the cage, giving it a negative charge, while the remaining unbalanced charge of the nuclei give the right side a positive charge. These induced charges create an opposing electric field that cancels the external electric field throughout the box.

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  SLC-40 with SpaceX Falcon 9 launch infrastructure. The four towers surrounding the rocket are lightning arresters, acting like a giant Faraday cage

See also

In Spanish: Jaula de Faraday para niños