The electric field of infinite sheets

In summary, when there is an infinite sheet of uniform positive charge parallel to an infinite, uncharged conducting sheet, the conducting sheet will have induced charges on both surfaces. These induced charges will make the electric field inside the conducting sheet 0, as the positive charges will cancel out the effect of the charged sheet. This is why the electric field inside a conductor placed in an external electric field is always 0.
  • #1
Conservation
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I am trying to understand electric fields of conductors.

Say that there is an infinite sheet of uniform positive charge; parallel to it lies a infinite, uncharged conducting sheet. What would the field look like between the sheets? Beyond the sheets? I would guess that the uniformly charged sheet would induce a uniformly distributed negative charge on the conducting sheet on the side closer to it, but I don't understand how the induced positive charge would distribute itself in the conducting sheet. Or how the positive charge would then affect the field.

Thanks.
 
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  • #2
Conservation said:
but I don't understand how the induced positive charge would distribute itself in the conducting sheet. Or how the positive charge would then affect the field.
It will be on the other surface(outer surface, far from the sheet) of the conducting sheet. These induced charges will make the E field inside the conducting sheet 0. Electric field lines from the charged sheet will terminate at the -ve induced charge on the conducting sheet and will reappear from the +ve induced charge on the other surface of the conducting sheet.
 
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  • #3
Okay. That makes sense; That would make E field coming out from the opposite surface same as the E field going in, and that's consistent with Gauss's law.

What I fail to see is how this distribution of induced charges will result a field of 0 inside the conductor. If there is an infinite positive surface charge on one side of the conducting sheet and infinite negative surface charge on the other side of the conducting sheet, shouldn't there be a field inside the conducting sheet?
 
  • #4
Conservation said:
shouldn't there be a field inside the conducting sheet?
Yes. And that field exactly cancels the field due to the charged sheet, making net E field inside the conducting sheet zero. This is why electric field inside a conductor placed in an external electric field is always 0.
 
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Related to The electric field of infinite sheets

1. What is an infinite sheet in terms of electric fields?

An infinite sheet is a theoretical construct used in physics to model a surface with uniform electric charge distribution. It is assumed to have infinite dimensions, meaning that it extends infinitely in all directions.

2. How is the electric field of an infinite sheet calculated?

The electric field of an infinite sheet can be calculated using the formula E = σ/2ε0, where σ is the surface charge density and ε0 is the permittivity of free space.

3. Is the electric field of an infinite sheet uniform?

Yes, the electric field of an infinite sheet is uniform and constant at all points in space. This is because the infinite dimensions of the sheet result in an equal amount of charge per unit area, leading to a constant electric field.

4. What is the direction of the electric field of an infinite sheet?

The direction of the electric field of an infinite sheet is perpendicular to the surface of the sheet. This means that the electric field lines are parallel and do not converge or diverge.

5. How does the electric field of an infinite sheet differ from that of a finite sheet?

The electric field of an infinite sheet is constant and uniform, while the electric field of a finite sheet varies depending on the distance from the sheet. Additionally, the electric field of an infinite sheet extends infinitely in all directions, while a finite sheet has a limited extent.

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