Induced Electric Field inside Faraday Cage

In summary, the conversation discusses the effects of a Faraday cage on electromagnetic fields. It is determined that a Faraday cage does not suppress internal fields, but only shields from external fields. This means that any electricity or electromagnetism experiment inside the cage should proceed normally, with the chamber walls acting as boundary conditions for the Maxwell equations. The question of whether the solenoid in the middle of the toroid would cause induction is also addressed, with the conclusion that the field will not get out if it is generated internally, but will not get in if it is an external field.
  • #1
TESL@
122
8
Imagine there is a hollow toroidal conducting chamber and a long solenoid in the middle. When we power the coil, does the induced electric field "propagate" inside the chamber? My prediction is that the changing flux will cause induction regardless of the cage.

Thank you.
 
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  • #2
A Faraday cage does not suppress electromagnetic fields inside it - it just shields from external fields.
Therefore any electricity/electromagnetism experiment inside a Faraday cage should proceed normally... the chamber walls you describe would be the boundary conditions for the Maxwel equations ... look up "wave guide".
 
  • #3
I am asking what if the solenoid is outside the chamber, in the middle of the toroid.
 
  • #4
TESL@ said:
I am asking what if the solenoid is outside the chamber, in the middle of the toroid.

Then reread Simon's first sentence :)
 
  • #5
His first sentence sounds to me like he has understood the question differently, as if the field is generated inside the chamber.
 
  • #6
TESL@ said:
His first sentence sounds to me like he has understood the question differently, as if the field is generated inside the chamber.

Simon Bridge said:
A Faraday cage does not suppress electromagnetic fields inside it - it just shields from external fields.

Note the bolded section of what Simon said ... that is your answer

if there is an internal field, it won't get out ... aka a microwave oven
if there is an external field it won't get in eg ...

Tesla18Dalek.jpg
cheers
Dave
 
Last edited:
  • #7
Thank you both.
 
  • #8
No worries :)
 

1. What is a Faraday Cage?

A Faraday Cage is a structure that is designed to block the entry or exit of electromagnetic fields. It is typically made of a conductive material, such as metal, and works by redistributing the electric charges within the cage, creating an electric field inside that cancels out any external electric field.

2. How does a Faraday Cage protect against electric fields?

As mentioned, a Faraday Cage works by redistributing the electric charges within the cage, creating an electric field inside that cancels out any external electric field. This means that any electric field that tries to enter the cage will be blocked, and any electric field that is generated inside the cage will be contained within it.

3. What is an induced electric field inside a Faraday Cage?

An induced electric field inside a Faraday Cage refers to the electric field that is created inside the cage due to the redistribution of electric charges. This induced electric field is equal in magnitude and opposite in direction to the external electric field that is trying to enter the cage.

4. How is the induced electric field inside a Faraday Cage calculated?

The induced electric field inside a Faraday Cage can be calculated using the equation E = σ/ε, where E is the electric field, σ is the surface charge density of the cage, and ε is the permittivity of the material. This equation shows that the induced electric field is directly proportional to the surface charge density and inversely proportional to the permittivity of the material.

5. Is the induced electric field always zero inside a Faraday Cage?

No, the induced electric field inside a Faraday Cage is not always zero. It is only zero if the external electric field is also zero. If there is an external electric field present, the induced electric field will be present inside the cage, but it will be equal in magnitude and opposite in direction, resulting in a net electric field of zero inside the cage.

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