When a charged particle couples through its field with another particle, and based on the dissimilar coupling strengths,it produces the 3 different potential functions ', namely, the Coulomb potential, weak coupling potential and Yukawa potential. The 3 potentials show the common characteristics: They are all periodic functions in time-space. Under the influence of those potentials, a particle takes periodic motions in space. The author notes that the electric field strength of an isolated charged particle would not show the divergent phenomenon.