Hi, What is a good interpretation of electric permittivity? If you look at Coulomb's law, it seems that the electric field due to a given source charge is inversely proportional to the permittivity of the medium where the charge is located. Furthermore, the electric permittivity of a simple dielectric medium is larger than the permittivity of free space, which leads to the result that its refractive index is > 1, i.e. the higher the permittivity of the medium, the slower EM waves will propagate through it. If I'm interpreting this right, then it seems kind of counterintuitive to call the quantity "permittivity". Why isn't it called electric "restrictivity" or something like that? What am I missing?