1. The problem statement, all variables and given/known data The electric field is zero within the conductor because the charges are all at rest in an electrostatic situation. But the electric field inside a cavity within the conductor is not necessarily zero because it isn't part of the conductor, as my book says. Then i encountered a topic about electrostatic shielding and it says that the electric field is zero inside an empty cavity with no charge. 2. Relevant equations ∫EdA= Qencl/εo 3. The attempt at a solution I tried using spherical gaussian surfaces inside the cavity: and EA=Qencl, Qencl=0,so E=0. I can make gaussian surfaces like this anywhere inside the cavity so E must be zero everywhere. But i think my solution is wrong because it means that Electric field is always zero. Let's say that we have a gaussian surface enclosing zero charge. Then even if there is an electric field outside, the electric field must be zero on the gaussian surface. Help please.