Calculating E-field Through Layers w/ Diff. Permittivities & Conductivities

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SUMMARY

This discussion focuses on calculating the electric field profile through layers with varying electrical permittivities and conductivities. The user seeks to understand how the total normal component of the electric field, denoted as ##E_{n,2} = E_0/\epsilon_{r,2}##, behaves across five thin layers and the surrounding medium. It is established that surface charge accumulation at the interfaces between layers influences the electric field, potentially creating a secondary electric field that requires further analysis. The steady-state condition is emphasized, where charge migration leads to a zero electric field inside layers with finite conductivities.

PREREQUISITES
  • Understanding of electric fields and their components
  • Familiarity with electrical permittivity and conductivity concepts
  • Knowledge of Maxwell's equations and boundary conditions
  • Basic principles of electrostatics and charge distribution
NEXT STEPS
  • Study Griffiths' textbook on electromagnetism for detailed explanations on electric fields in layered media
  • Learn about calculating surface charge densities at interfaces between different materials
  • Research the concept of the Displacement field (D) and its relationship to electric fields in dielectric materials
  • Explore numerical methods for simulating electric fields in multi-layered structures
USEFUL FOR

Electrical engineers, physicists, and students studying electromagnetism, particularly those interested in the behavior of electric fields in layered dielectric materials.

ThomasAnderson
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I'm trying to understand how the total electric field changes as it passes through layers with different electrical permittivities and conductivities (as shown in the linked figure). The rectangular prism layers are assumed to be very thin. The conductivities ##\sigma## and relative permittivities ##\epsilon_r## for the 5 layers as well as the surrounding medium are labeled. The external field ##E_0## is uniform. I'm hoping to find the profile of the total normal component of the E-field along the line A-A'.

I assumed that the profile would have a stepped pattern as shown in the right panel. For example, the electric field normal component inside layer 2 would be ##E_{n,2}=E_0/\epsilon_{r,2}##, and similarly for the other layers.

However, I also recall learning that there is a surface charge accumulation that occurs at the interfaces between each layer, due to the difference in conductivities. If I understand correctly, these surface charges create a secondary electric field. I don't know if I need to find this secondary field, and I'm not sure how I would calculate it. I would appreciate some guidance on this problem!

https://i.stack.imgur.com/UHQ7L.png
 
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Do things vary with time or are you interested in steady state (after system settles)?
 
hutchphd said:
Do things vary with time or are you interested in steady state (after system settles)?

I was interested in the steady state
 
For any finite conductivities, the charge will migrate to the opposing surfaces and the field inside will be zero (ignoring edge effects). Not very interesting?

For all conductivities zero the Displacemant field D will be E0 and the local E will be εD rE0 in each slab. I think Griffiths does a nice job on this general subject.
 
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