Induced charge on a solid metal sphere

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Discussion Overview

The discussion revolves around the concept of induced charge on a neutral metal sphere when it is enclosed by a uniformly charged metal shell. Participants explore the implications of electric fields and charge distribution within the spheres, focusing on theoretical and conceptual aspects of electrostatics.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asserts that charges on a metal sphere must reside on the surface to maintain no electric field within the metal, questioning whether a neutral sphere would have induced charges when enclosed by a charged shell.
  • Another participant suggests that there might be a negatively charged layer on the surface of the neutral sphere, followed by a positively charged layer beneath it, but acknowledges uncertainty in this hypothesis.
  • A third participant states that there is no electric field inside a charged metal shell, implying that the neutral sphere would not experience any change.

Areas of Agreement / Disagreement

Participants express differing views on whether the neutral sphere will experience induced charges, with some proposing potential charge distributions while others argue that no effect will occur due to the properties of electric fields in metal shells.

Contextual Notes

The discussion includes assumptions about the behavior of electric fields in conductive materials and the nature of charge distribution, which may not be fully resolved or agreed upon by participants.

luhar
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I understand clearly that if a metal sphere is charged then the charges must reside on the surface because that is the only way there is no electric field within the metal. However if you imagine a neutral metal sphere, and let's say it is suddenly enclosed by a uniformly charged metal shell concentric with the neutral sphere (radium of shell greater than sphere). In this case will it induce charges on the surface of the neutral sphere? I cannot see how it would since if it does then these would have to reside on the sphere's surface and then the remaining charge of opposite polarity on the sphere would have no place to go! If that is true then it it is a little strange that despite the presence of an electric field on the surface of the sphere (due to the presence of the charged shell) and the free electrons within it nothing happens!
 
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I suspect that either nothing will happen, or there will be a layer on top that is negatively charged, followed by a layer immediately below (on atomic scales) that is positively charged. The configuration will somehow adjust itself so that there is no field inside the bulk of sphere. (Note: I could be completely wrong.)

[Motivating source: Jackson's Classical Electrodynamics, section "Some Remarks on Idealizations in Electromagnetism"]
 
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luhar said:
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enclosed by a uniformly charged metal shell concentric with the neutral sphere
There is no E field inside a charged metal shell, so nothing will happen to the enclosed sphere.
 

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