Fields of an extended charge distribution a general distribution of charges in space is usually described by an electric charge density p(r) Once p(r) is given, one can calculate the electric field regenerated ATE0r-re(r-ridr E(r)=∑E2=1 Remarks (1)Application of this expression to get e is techni cally more complicate, since it involves a summation of vectors (2)There is another way to obtain e more efficiently (thru V)