a. Dipole b. Set of a finite number of point charges c. A uniformly charged rod d. A uniformly charged ring e. A uniformly charged disk f. A solid sphere uniformly charged throughout its volume g. A spherical shell with a uniformly charged surface Solution its better to choose A solid Sphere uniformly charged throughout its volume. because, it just acts as a point charge. and there will be no change in either Electric field, Potential or Force etc except at the distance from centre to R..