Hi, could anyone help me understand the permittivity of free space in Gauss's Law: [itex]\Phi[/itex] = q/[itex]\epsilon[/itex]0 If you consider a point charge in a box then I think it tells you how easy it is to establish an electric field in free space. But what happens if the medium is not free space - say you put the charge in a box with a dense medium. Does this mean an electric field will be harder or easier to establish? So does epsilon zero give you the situation where the electric field or flux will be the highest? Thank you for any help offered.