Figure 2.32 shows a charge array known as an electric quadrupole. For a point on the axis of the quadrupole, obtain the dependence of potential on r for `r//a gt gt 1` , and contrast your results with that due to an electric dipole, and an electric monopole (i.e., a single charge).

Explanation

For large r, quadrupole potential goes like `1//r^(3)`, dipole potential goes like `1//r^(2)` , monopole potential goes like 1/r.