Induced charge on a solid metal sphere

luhar

All

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 lets 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!

cwilkins

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"]

Naty1

no. no. [I was required to submit a least four characters...]

Meir Achuz

There is no E field inside a charged metal shell, so nothing will happen to the enclosed sphere.