Block all signals with a Faraday cage

What is a Faraday cage?

A Faraday cage or faraday shield is an enclosure used to block electromagnetic fields. The construction is made of electrically conductive material, such as copper or iron, which prevents static fields from penetrating inside the housing. Originally a Faraday cage was an actual cage, but today this term is used for all enclosures and spaces that exclude electromagnetic radiation.

A concept in the making

Before Michael Faraday published the scientific principles behind the Faraday cage, there were already predecessors who were working on the phenomenon. In 1755, Benjamin Franklin slowly lowered a cork ball, hanging by a silken thread, into an electrically charged can. The ball simply drops down, without any remarkable phenomena. When he repeated the experiment, but on the outside of the can, he noticed that the ball was being pulled towards the can. Franklin’s conclusion: the charge of the can can only affect other charges outside of that can.

Where do we find Faraday cages?

Microwave oven

This metal box acts as a Faraday cage. Put your cell phone in a microwave and you will not receive a cell phone signal. Disclaimer: Never put your mobile phone in a microwave oven and certainly don’t turn it on if you do.

MRI scanner room

The room in which an MRI scanner is located is always a Faraday cage. In addition, the unwanted waves within the cage are damped.

Hitchhike

Elevators and other spaces with conductive frames and walls simulate the effect of a Faraday cage, leading to loss of signal and dead zones for users of cell phones, radios and other electronic devices requiring external electromagnetic signals.

Watches

Watches are often equipped with a Faraday cage to protect them from electromagnetic radiation. Exposing a watch to electromagnetic waves can cause it to malfunction or even stop the movement.

Is a car a Faraday cage?

In short, no. To work like a Faraday cage, something has to be a closed metal object. The car windows allow electric and magnetic fields to still penetrate. The roof is metal, and power is often safely routed to the ground through the rest of the car. Strictly speaking, a car is not a Faraday cage, but it is a good current conductor. If you have to be on the road during an intense storm, you will be safe if lightning strikes your car.

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Even in a Faraday cage we provide a signal!

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