I am just going to randomly dump things here, no structure. It is exhausting to maintain a structure. - When calculating electric potential V for a point in space, the reference point is often assumed to be at infinity. - The constitutive electromagnetic parameters of a material medium are $\epsilon , \mu, \sigma$ (electrical permittivity, magnetic permeability, conductivity) - Homogenous - Parameters do not vary from point to point - Isotropic - Independent of direction -