Electric potential and current around an insulator

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SUMMARY

This discussion centers on the behavior of electric potential and current around an insulator with a crack in a conducting surface. The user explores how the presence of a gap affects current flow, referencing key equations such as V = (1/4πε)(Q/r) and J = σE. The primary challenge identified is the need for boundary conditions to accurately model current behavior around the crack, particularly in low-conductivity materials. The user seeks clarification on whether treating the hole as a radiating dipole is applicable in scenarios involving poor conductors.

PREREQUISITES
  • Understanding of electric potential and current density equations
  • Familiarity with boundary conditions in electromagnetic theory
  • Knowledge of electric permittivity and its effects on current flow
  • Basic concepts of dipole radiation and its relevance to electrical engineering
NEXT STEPS
  • Research boundary conditions for current flow in conductive materials with gaps
  • Study the effects of electric permittivity on current density in non-ideal conductors
  • Learn about the modeling of radiating dipoles in electromagnetic simulations
  • Explore numerical simulation tools for analyzing electric fields around discontinuities
USEFUL FOR

Electrical engineers, physicists, and students studying electromagnetism, particularly those interested in the behavior of electric fields and currents in conductive materials with imperfections.

meldraft
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Hi all,

I am trying to run a simulation, and I have come across a theoretical question.

Let's say that you have an electric charge producing a potential on a conducting surface (let's assume it's infinite). Now, if you make a crack in the surface so that there is a gap (filled with air for example), you create an area where the current can't pass through.

The equations say that the potential inside the crack will change because of the different electric permitivity, while on the other side it won't be affected at all.

My problem is how the current is supposed to move. If I just integrate for the current density I can get the current vectors on the surface:

V=\frac{1}{4\pi\epsilon}\frac{Q}{r}
E=-\nabla{V}=\frac{1}{4\pi\epsilon}\frac{Q}{r^2}
J=\sigma E
I=\int{J\cdot dA}

, but they look like they would without the crack, with the exception that no current passes through the crack.

Current moves along the electric field, which, in my case, just has a gap where the crack is, and its shape is otherwise unaffected.

I know that current is supposed to go around the crack, much like a fluid would, so I probably need a boundary condition for the crack. Does anybody know how I should go about it?
 
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I fear the answer is more complicated than you are hoping for. If you have currents through a conducting sheet with a hole (crack, gap, slot, etc.), then the hole will http://en.wikipedia.org/wiki/Slot_antenna" . As a first order approximation, you can treat the hole as a radiating dipole oriented perpendicular to the conducting surface and located at the hole's center.
 
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In my problem however, the material is a really bad conductor and the current is very small. Is this still applicable in that case?
 

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