Does the use the use of ε0 imply that it is for vacuum?

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Discussion Overview

The discussion revolves around the implications of using the permittivity of free space (ε0) in equations related to electrical and magnetic fluxes, particularly in different materials. Participants explore whether Maxwell's equations apply universally or are limited to specific contexts, such as vacuum or air.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant expresses confusion about whether equations for electrical and magnetic fluxes apply only in free air or in other materials as well.
  • Another participant asserts that ε0 is specifically for a vacuum but can be approximated in air due to its relative permittivity being close to 1.
  • It is noted that Maxwell's equations are applicable in all contexts, though some may present them specifically for vacuum conditions.
  • A participant mentions that ε0 is typically accompanied by εr in formulas, and if εr is not specified, it is assumed to be unity, indicating conditions in free space.
  • One participant states that the electric flux distribution remains consistent in isotropic materials only under certain boundary conditions and fixed geometries.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the applicability of Maxwell's equations across different materials, with some arguing for universal applicability and others suggesting limitations based on context.

Contextual Notes

There are unresolved assumptions regarding the conditions under which Maxwell's equations are applied, particularly concerning the nature of the materials involved and the implications of boundary conditions.

ugenetic
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I found most literatures on Electrical or Magnetic fluxes maddeningly unclear about the MATERIAL in which the equations are applied. In free air only? or not?

I would like to know if the following 2 statements are true
the electrical flux generated by a single charge will look the same in all (uniform) materials.
the electrical field E generated by a single charge will change from one material to another depends on εr.

I m guessing maxwell equations are really for conductors and air?
 
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##\epsilon_0## is for a vacuum. It is often used as an approximation in air since the relative permativity of air is very nearly 1.

You should be able to tell whether a vacuum is intended or not by the context.

Maxwels equations are for everywhere.
Some people just write them out for the vacuum case.
 
In a formula, εo is always accompanied by εr.

Similarly, μo is always accompanied by μr.

If the relative constant is not explicitly shown, it is taken as unity (meaning its value in free space).
 
The electric flux distribution will be the same for anyone isotropic material only if the boundary conditions are perfect conductors and/or insulators, and the geometry is fixed.
 
OH WOW, so clear, thank you all. I am writing them down.
 
Last edited:

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