Show that the potential V at a point is the average value of V07) over a spherical surface of radius R centered at the point: f _ V(da 1 ' Vav '*R = V d I rz dd 47TI2 fR (T?) a assuming the charge distribution is external to the sphere7 is, there is no charge inside the sphere. 'W hat about the average potential over a spherical volume due to charges outside the volume