# Electric Field Shielding: Does a Conductor Shield Inside?

• arestes
In summary: So, the answer is yes, a hollow conductor does shield off electric fields inside it. However, it would not work if the electric field was coming from inside the conductor, as opposed to outside the conductor.
arestes
Hi.
I was reading about conductors in electrostatic equilibrium and how it makes sense that they have zero electric field inside the material even when an external charge is brought near. The charge density of the material just rearranges itself to cancel. Then I searched for hollow conductors since they behave differently.

However, the derivations of the fact that there is zero field inside a conductor (both hollow and solid) uses symmetry.
Using Gauss' law and this symmetry, when there's no charge outside, it can easily be seen that the magnitude of the field is the same at a specified distance of the center and it clearly means that a gaussian surface enclosing no charge implies a zero field.
I am worried of this last step because when an external charge is brought near, there is no spherical symmetry anymore. ¿Is the field inside shielded completely? Or, ¿is this just an approximation of a "Faraday Cage"? (does it work the same when the sphere is hollow and when it's solid?).

I found a Wiley resource that says it's not zero:

But I also found another resource (both on google) that asks the same but, the answer it gives is zero:
https://www.liveworksheets.com/oi1233136al

(By the way, this other question is in many websites but I'm not sure what book this has been taken from, does anyone know?).

So... does a (hollow or solid) spherical conductor with an external point charge completely shield off electric fields inside it?
Also, I have a feeling it doesn't. I read wikipedia's article about image charges with this method of "mirror images" and it's supposed to act as if there was another charge inside of opposite sign. Does this work with solid or hollow. I couldn't find.

ThanksI

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arestes said:
However, the derivations of the fact that there is zero field inside a conductor (both hollow and solid) uses symmetry.
No it does not. It uses Gauss's theorem.

BvU said:
No it does not. It uses Gauss's theorem.
Yes, that's what I say, but Gauss' law alone is not enough if we can't factor out the electric field outside the integral due to symmetry, right?

Unless there are charges inside the hollow conductor, the electric field inside the cavity is zero. Whoever put a box around (c) in Wiley's resource goofed.

vanhees71
arestes said:
Yes, that's what I say, but Gauss' law alone is not enough if we can't factor out the electric field outside the integral due to symmetry, right?
Gauss's law guarantees that there is no charge inside a Gaussian surface that is drawn just under the surface of the conductor. You need to add that if there were an electric field inside the cavity, then one should be able to draw an electric field line from one point A of the cavity to another point B. However that means that there is a potential difference VAB from one point of the conductor to another which violates the fact that conductors in static conditions are equipotentials. This argument is also known as invoking the Uniqueness Theorem in electrostatics.

vanhees71 and hutchphd

## 1. What is electric field shielding?

Electric field shielding is the process of reducing or eliminating the effects of an electric field on a specific area or object. This is typically achieved by using a conductor to redirect the electric field away from the protected area or object.

## 2. How does a conductor shield inside?

A conductor shields inside by creating an equal and opposite electric field within its material. This cancels out the electric field from an external source, effectively shielding the inside area from its effects.

## 3. What materials are commonly used for electric field shielding?

Conductive materials such as metals (e.g. copper, aluminum) and conductive coatings (e.g. conductive paint, conductive fabric) are commonly used for electric field shielding. However, the effectiveness of the shielding depends on the conductivity and thickness of the material.

## 4. Can a conductor shield inside from all types of electric fields?

No, a conductor can only shield inside from electric fields that are static or low frequency. High frequency electric fields, such as those from radio waves or microwaves, can penetrate through conductors and are more difficult to shield.

## 5. Are there any safety concerns with electric field shielding?

Yes, there are safety concerns with electric field shielding. If the electric field is not properly redirected or grounded, it can accumulate and potentially cause harm to individuals or damage to equipment. It is important to consult a professional when designing and implementing electric field shielding.

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