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 recieve 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 havent touched the subject in quite a while im not sure. i think that there isnt mirroring effect unless the conductive surface is grounded (because only then it recieves 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.