Excess charge on insulators and conductors

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Discussion Overview

The discussion revolves around the behavior of excess charge on insulators versus conductors, specifically exploring why excess charge remains localized on insulators while it spreads uniformly across the surface of conductors. The participants inquire about the underlying principles, including the role of electrostatic potential and the nature of mobile charges in these materials.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants assert that excess charge on an insulator remains in place, while on a conductor, it spreads uniformly across the surface.
  • There is a question regarding the explanation of this behavior in terms of electrostatic potential.
  • One participant queries why charge does not remain localized in conductors as it does in insulators.
  • Another participant explains that conductors have mobile charges (conduction electrons) that can move freely, unlike insulators, which have very few mobile charges.
  • It is noted that mobile charges in conductors tend to move away from each other and respond to electric fields, which influences their distribution.

Areas of Agreement / Disagreement

Participants generally agree on the basic distinction between the behavior of charge in insulators and conductors, but the discussion remains open regarding the detailed mechanisms and implications of these behaviors.

Contextual Notes

There are unresolved questions about the specific role of electrostatic potential and the conditions under which these behaviors occur, particularly regarding the electric field inside conductors under static conditions.

Ruby_338
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From what I've learned, excess charge on an insulator stays where it is but excess charge on a conductor spreads uniformly throughout its surface. Why does this happen? Can this be explained in terms of electrostatic potential?
 
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Ruby_338 said:
From what I've learned, excess charge on an insulator stays where it is but excess charge on a conductor spreads uniformly throughout its surface. Why does this happen? Can this be explained in terms of electrostatic potential?

Sure! Under static condition, what is the electric field inside an idealized conductor?

Zz.
 
I mean, why doesn't it stay in one place like in an insulator?
 
Ruby_338 said:
I mean, why doesn't it stay in one place like in an insulator?

Do you know what makes a conductor a conductor, and an insulator and insulator? The amount of mobile charges in it! Insulators do not have any (or many) mobile electrons (or holes), while a conductor/metal, by definition has these things called "conduction electrons" which can move around very easily and are not tied to any particular sites in the conductor.

When there are mobile charges, they tend to move as far away from one another as possible, AND, they tend to follow where there are, if any, electric fields. It is why I asked if you know what is the electric field inside a conductor under static condition.

Zz.
 
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I see. Thanks.
 

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