Faraday Cage: If Car acts as Faraday Cage, how come cell phone works inside the car?

Answer 1

A Faraday cage is a metallic enclosure that prevents the entry or escape of an electromagnetic field (EM field). An ideal Faraday cage consists of an unbroken, perfectly conducting shell. This ideal cannot be achieved in practice, but can be approached by using fine-mesh copper screening. For best performance, the cage should be directly connected to an earth ground.

A car is not a good Faraday Cage for two reasons. The first one is that it's not 'unbroken' ... thereby allowing signals to enter and exit. The second reason is that it isn't grounded ... it's up on tires (which are insulators), which means the metal of the car's 'cage' ~could~ act like a giant antenna if the signal was strong enough.

And you'll notice that your phone gets MUCH better reception when held near a window, rather than down near the floor of the vehicle over the drive train; the center of the vehicle is the most likely position to demonstrate the 'cage effect'.

Answer 2

Faraday Cage Cell Phone

Answer 3

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RE:
Faraday Cage: If Car acts as Faraday Cage, how come cell phone works inside the car?

Answer 4

A car operates as a Faraday cage fo lightinings or other forms of static electricity.

A cell phone operates on radio frequency, and in such a case there enter into play the frequency/wavelenght. If the wavwlenght is smaller than the openings in tha Faraday cage ( in the case of a car the windovs since the glass is transparent to radiowaves)
then they cas pass un-impeded through the glass and you can send/receive a call.

Answer 5

Because of the glass (and other things), a car is NOT a good Faraday cage. You can use a portable radio inside a car.

Answer 6

The weavelength of the radio signal is small enough to get out through the window.