Consider a region inside which there are various types of charges but the total charge is zero. At points outside the region a) the electric field is necessarily zero b) the electric field is due to the dipole moment of the charge distribution only c) the dominant electric field is proportional to 1/r3 for large r, where r is the distance from an origin in this region d) the work done to move a charged particle along a closed path, away from the region, will be zero
When there are various types of charges in a region, but the total charge is zero, the region can be supposed to contain a number of electric dipoles. Therefore, at points outside the region, the dominant electric field ∝r31 for large r
