The direction of vector \(\vec A\) is radially outward from the origin, with \(\left| \vec A \right|\; = \;k{r^n}\) where \({r^2} = {x^2} + {y^2} + {z^2}\)and \(k\) is a constant. The value of n for which \(\vec\nabla .\;\vec A\; = \;0\)