Electric field and gauss law for different models of sphere

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Discussion Overview

The discussion revolves around the application of Gauss's law to different models of spheres, particularly focusing on the electric field behavior in scenarios involving charges placed within or on the surfaces of spherical shells and solid spheres. Participants explore theoretical implications and practical realizations of charge distributions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether a charge placed at the center of a spherical shell would come out to the surface, seeking clarification on the validity of this statement.
  • Another participant mentions that the electric field inside a solid sphere with charge uniformly distributed on its surface is zero, while also referencing a different expression for the electric field inside a solid sphere, Kqr/R^3, suggesting a potential confusion between different charge distributions.
  • There is a discussion about the difference between a charge uniformly distributed on the surface of a solid sphere and a symmetrical spherical distribution of charge.
  • Participants explore how to achieve a spherically symmetrical distribution of charge, with one suggesting that it could be done by placing charges at the center of a solid sphere, while another humorously proposes mixing charges to achieve uniformity.
  • A later reply introduces a mathematical condition for spherical symmetry in charge distribution and speculates on practical examples, such as neutron stars, where charge distribution might be spherically symmetric.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the implications of charge placement and distribution, with no consensus reached on the correctness of the statements about electric fields or the methods to achieve spherical symmetry.

Contextual Notes

There are unresolved assumptions regarding the nature of charge distributions and the conditions under which the electric field behaves as described. The discussion also reflects varying interpretations of Gauss's law in different contexts.

exuberant.me
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Hello all! I actually have a few doubts regarding "gauss law" when applied "for different models of sphere"

First, If we place a charge 'Q' inside a spherical shell at the center (somehow) then it should come out to its surface that means in no way can we do it. True or False?

Next,

Considering a solid sphere having a charge Q uniformly distributed on its outer surface. Thus everywhere inside it is the electric field equal to 0.

But i have somewhere read that the electric field inside a solid sphere is Kqr/R^3.

Or is it that , there is a difference in these two statements
"A charge uniformly distributed on the surface of a solid sphere" and
"A symmetrical spherical distribution of charge" ?

Also, How can we get a spherical symmetrical distribution of charge?
. By placing the charge at the center of the solid sphere? (which is again impossible i guess)

I'll be greatly thankful if someone clears these brain storming doubts?
 
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hello exuberant.me! :smile:

(try using the X2 button just above the Reply box :wink:)
exuberant.me said:
First, If we place a charge 'Q' inside a spherical shell at the center (somehow) then it should come out to its surface that means in no way can we do it. True or False?

sorry, no idea what you mean :redface:
But i have somewhere read that the electric field inside a solid sphere is Kqr/R^3.

Or is it that , there is a difference in these two statements
"A charge uniformly distributed on the surface of a solid sphere" and
"A symmetrical spherical distribution of charge" ?

yes … Kqr/R3 is for a charge uniformly distributed throughout the volume (use gauss law! :wink:)
Also, How can we get a spherical symmetrical distribution of charge?
. By placing the charge at the center of the solid sphere? (which is again impossible i guess

no, by chucking the charges in, and giving them a good old stir

like making a pudding :smile:
 
tiny-tim said:
like making a pudding :smile:

With no lumps, of course... nice and smooth...
 
exuberant.me said:
Also, How can we get a spherical symmetrical distribution of charge?
mathematically,
\frac{\partial \rho}{\partial \theta} = \frac{\partial \rho}{\partial \phi} = 0
and practically how this could happen for a solid sphere with fixed charges? ...err... maybe in Neutron stars that have a surplus of electrons? The electrons wouldn't be fixed, but in equilibrium the charge distribution would be spherically symmetric... unless it was a pulsar?

So you just have to make a neutron star :) easy-peasy.
 

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