Integral form of Gauss' Law, Parallel Plate Capacitor

In summary, the integral form of Gauss' Law does not hold for a closed surface between parallel plate capacitors with vacuum space between them, as it is not useful in solving for electric field, surface charge density, or total charge due to the integration over the entire surface area. This is because a non-zero charge density cannot give rise to an electric field that vanishes everywhere, and the integral form of Gauss' Law does not allow for the separation of flux going in and out of the surface, making it impossible to find the surface charge density.
  • #1
jajay504
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Homework Statement


If one were to consider a parallel plate capacitor with a distance d between them connected to a battery and a vacuum space between the plates. Will the integral form of Gauss' Law to any closed surface between the plates that does not cross either plate hold? If not, what in Gauss' Law would prevent this from working?

Homework Equations



Gauss' Law

The Attempt at a Solution


I know that Gauss' law works in cases where there is high degree of symmetry.
I also know that the integral form describes an integration of fields. However, after a function is integrated, a lot of information is lost. A non-zero charge density cannot, under any circumstances, give rise to a an electric field that vanishes everywhere.

 
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  • #2
There's a distinction between a Law being valid (ie, "holding" true), and being useful.
Gauss' Law would merely say that there's zero total charge inside the surface ... which we already knew ... there's only vacuum in there, after all.
But since you need to integrate over the whole surface Area, you can't find the flux inward thru the top separately from the flux that leaves out the bottom => so you can't find the surface charge density. It still "works" in the sense that it doesn't lie ("0=0"), but it doesn't "work" in the sense of being useful to solve for E, or σ, or Q ...
 

1. What is the integral form of Gauss' Law?

The integral form of Gauss' Law is a mathematical equation that describes the relationship between the electric flux through a closed surface and the charge enclosed within that surface. It is often written as ∮𝐸⋅𝑑𝐴 = 𝑄/𝜖₀, where ∮𝐸⋅𝑑𝐴 represents the electric flux, 𝑄 represents the enclosed charge, and 𝜖₀ is the permittivity of free space.

2. How is the integral form of Gauss' Law used to calculate the electric field?

The integral form of Gauss' Law can be used to calculate the electric field in situations where there is symmetry, such as a parallel plate capacitor. By choosing a closed surface that follows the symmetry of the system, the electric flux can be easily calculated and used to solve for the electric field. For example, in a parallel plate capacitor, the electric field can be found by dividing the charge on one plate by the area of the plate and the permittivity of free space.

3. What is a parallel plate capacitor?

A parallel plate capacitor is a simple electrical device that consists of two parallel conducting plates separated by a small distance. When a voltage is applied to the plates, one becomes positively charged and the other becomes negatively charged. This creates an electric field between the plates, and the capacitor can store energy in the form of electric potential energy.

4. How is the integral form of Gauss' Law applied to a parallel plate capacitor?

In a parallel plate capacitor, the integral form of Gauss' Law can be applied by choosing a closed surface that follows the symmetry of the system. This closed surface would typically be a cylinder that includes one of the plates and extends to the other plate. By calculating the electric flux through this surface and equating it to the enclosed charge, the electric field between the plates can be found.

5. What is the significance of the integral form of Gauss' Law in the study of electromagnetism?

The integral form of Gauss' Law is one of the four Maxwell's equations, which are fundamental laws in the study of electromagnetism. It helps to relate the electric field to the distribution of electric charge, and is essential in understanding the behavior of electric fields in various situations. It is also used in the design and analysis of electrical systems, such as parallel plate capacitors, and is a crucial tool in the study of electricity and magnetism.

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