Electric field at a point within an infinite volume charge distribution

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Homework Help Overview

The discussion revolves around the electric field generated by an infinite volume charge distribution, with references to concepts from "Electricity and Magnetism" by Purcell. The original poster explores the potential dependency of the electric field on distance from the center of the distribution.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to reason about the electric field's behavior based on symmetry and integration of electric fields from infinite plane distributions. They question whether this leads to a linear dependency on distance. Other participants raise considerations about the implications of higher dimensions on the electric field behavior.

Discussion Status

The discussion includes various perspectives on the nature of electric fields in infinite charge distributions, with some participants questioning the assumptions made by the original poster. There is an acknowledgment of the complexity of the topic, particularly in relation to higher dimensions, and the conversation remains open without a clear consensus.

Contextual Notes

The original poster mentions a lack of multivariable calculus knowledge, which may limit their ability to fully engage with the mathematical aspects of the problem. Additionally, there is a humorous exchange regarding the implications of considering dimensions beyond the conventional three.

Villhelm
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I started reading through "Electricity and Magnetism" by Purcell and came across the derivations for infinite line and infinite plane charge distributions and noticed the former has a 1/r dependency (on perpendicular distance from the wire) and a constant value for the plane.

Would an infinite charge volume have a linear dependency on r, eg constant*r?

I don't have the multivariable calculus knowledge to work this through myself to see, but this is just out of interest right now ...

I've thus far reasoned that this might be so by considering that E=0 at the center of the distribution (from symmetry) and then moving a distance r out from the center would produce a cuboid of charge, an infinite plane face and thickness r and thus the flux would be like taking the single variable integral of a bunch of infinite plane electric fields (which I assume have a constant electric field strength as in the book) from 0->r ... thus introducing a linear r dependency?

Is this ad hoc reasoning ok or am I way off?

I expect to cover the calculus sometime in the next few weeks anyway so I can hopefully form the equations up myself ... but this is bugging me since I thought about it first :(
 
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unless you're considering the electric field in the 4-th dimension, the electric field for an infinite volume distribution has to be 0. An infinite charge volume would stretch out over the entire universe and the test charge would have to be inside the conducting material unless it was outside the universe (huh??) or in a higher dimension (huh??)
 
No need to be flippant about it, I find that considering and trying to extend/generalise everything I come across even it if seems or is unphysical to be useful mental exercise.

So, my question becomes:

If there were 4 or more spatial dimensions, then would the above hold true?
 
sorry if i came off as flippant, i was actually trying to be humorous (evidently, that failed)

im a student barely ahead of you so i have no clue about its behavior in 4d
 
Ah, ok ... I read overtones on the (huh?) that were incorrect, sorry about that. :redface:

Anyway, there are bigger fish to fry at this time of year so I'll consider this effectively closed.
 

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