Help understanding Faraday cages..... I have a basic understanding of electrostatics but can't quite get my head around how a Faraday cage works. If you take a hollow metal sphere for example and bring an external source charge towards the sphere why is there no electric field on the inside of the conductor? I know if you take a Gaussian surface of the inside then this automatically tells you there is no E-field but this gives me little intuition to what is actually happening. If the external source charge is positive then it will have electric field lines which start on the source charge and end at infinity which go radially outwards. What happens when these field lines come across the metal shell - do they go in and then back out giving zero net flux or can they physically not enter the shell? I did read somewhere that the electrons on the shell rearrange themselves to cancel the E-field of the external source charge but what exactly is meant by "cancel" - do the electrons create there own E-field or something? Many thanks in advance for any help.