Charge inside a conductive shell

[Zipi]

Hi there , I'm a bit rusty on the subject so I have 2 questions , although they are quite similar.

Anyways first one :
Lets say i have a sphere charged with Q , and around that sphere I have a conductive shell (also a shpere) at some distance from our charged sphere . The conductive shell is ungrounded. So my question is this , would there be an electrical field outside of the conductive shell ?

personally i think there would be a field outside , and only if the shell was grounded there'd be no field outside (because then the shell would receive a -Q charge and it would nullify any field outside).

Second question:
Lets say we have an infinate conductive surface , the surface is ungrounded. and below that surface at a distance 'h' we have an infinate wire with a linear charge charge density of D. so my question is quite similar.

so the question is ,would there be an electrical field above the surface , also if not or if yes , would there be a mirroring effect (i've translated it from a diffrent language so not sure if its the same in english so i'll explain). mirroring effect - basically we treat it as if there is another wire at the same distance behind the conductive surface , the field behind the surface is zero , but below it we look at the electrical field as if its a result from two wires.

and to make things easier to understand , assuming I'm not too good at explaining , i drew some pictures :P http://img98.imageshack.us/my.php?image=pewpewpewhe6.jpg


anyways here again i have my idea but since i haven't touched the subject in quite a while I am not sure.
i think that there isn't mirroring effect unless the conductive surface is grounded (because only then it receives an actual charge) and i see no reason that the conductive surface would block the electrical field above it

dont know if it may seem like a homework question , but its more of a theoretical question for myself.

 

[Defennder]

Lets say i have a sphere charged with Q , and around that sphere I have a conductive shell (also a shpere) at some distance from our charged sphere . The conductive shell is ungrounded. So my question is this , would there be an electrical field outside of the conductive shell ?

personally i think there would be a field outside , and only if the shell was grounded there'd be no field outside (because then the shell would receive a -Q charge and it would nullify any field outside).

Yes, there will be an external electric field. Gauss law says so.

Lets say we have an infinate conductive surface , the surface is ungrounded. and below that surface at a distance 'h' we have an infinate wire with a linear charge charge density of D. so my question is quite similar.

so the question is ,would there be an electrical field above the surface , also if not or if yes , would there be a mirroring effect (i've translated it from a diffrent language so not sure if its the same in english so i'll explain). mirroring effect - basically we treat it as if there is another wire at the same distance behind the conductive surface , the field behind the surface is zero , but below it we look at the electrical field as if its a result from two wires.

anyways here again i have my idea but since i haven't touched the subject in quite a while I am not sure.
i think that there isn't mirroring effect unless the conductive surface is grounded (because only then it receives an actual charge) and i see no reason that the conductive surface would block the electrical field above it

Yes there will be an electric field. You can evaluate it by invoking the method of images. The conductive plate doesn't have to be grounded.

 

[astrokreng]

I can confirm that your understanding is correct. In the first scenario, there would be an electric field outside of the conductive shell because the shell is ungrounded. This means that the charges on the shell are not redistributed and thus the electric field outside is not canceled out. However, if the conductive shell were grounded, the electric field outside would be canceled out because the charges on the shell would redistribute to neutralize the external field.

In the second scenario, there would also be an electric field above the conductive surface, as the surface is ungrounded and the wire below it has a linear charge density. The mirroring effect would only occur if the conductive surface were grounded, as this would redistribute the charges on the surface and create a mirrored electric field. Otherwise, the conductive surface would not affect the electric field above it.

I appreciate your curiosity and theoretical thinking in this matter. It is always important to question and understand concepts in science, even if it may seem like a homework question. Keep up the good work!