The expression of Coulomb law F 1 2Q A兀So Where 8 is the permittivity at vacuum(. 854x10-12farad/m) Discussion 1) Whether the inverse square law is accurate or not To be determined by the experiment 2)Only valid for stationary point charges 3)Vector property for the interaction Comment: a) The limitation of the theory is depending upon the validity of 1) b) The complication of the complete theory of electric field is due to 2 and 3)The expression of Coulomb law: r r Q Q o a b o F   2 4 1   = Where o  is the permittivity at vacuum (8.854x10-12farad/m) Discussion: 1) Whether the inverse square law is accurate or not. To be determined by the experiment 2)Only valid for stationary point charges 3) Vector property for the interaction Comment: a) The limitation of the theory is depending upon the validity of 1) b) The complication of the complete theory of electric field is due to 2) and 3)