Electrostatic Fields in Matter

2. For a sheet of charge, with charge per unit area of σ, Gauss’slaw gives the field as σ/ɛ 0 .So E free = σ fɛ 0= 4.07 × 10 3 Vm −1and E bound = σ bɛ 0= 2.27 × 10 3 Vm −13. The polarisation ⃗ P is defined as the total dipole moment per unitvolume. In order to calculate ⃗p, the moment of an individualdipole, we would need to know the number of dipoles per unitvolume.12