If an electromagnetic field can be represented by a pure electric wave (E-wave or TM wave, transverse magnetic field) or a pure magnetic wave (H-wave or TE wave, transverse electric field), then as a boundry value problem, when the operating frequency tends to zero, the electromagnetic field will be re-duced to an electrostatic or a magnetostatic field, respectively. Hence the solution of such an electromagnetic problem can easily be obtained from that of the corresponding static problem, because there exists an one-to-one correspondence between the terms of the series solution of the electromagnetic problem and those of the series solution of the static problem, and therefore we can obtain one series from the other, using the rales of determining the integration constants in the unknown series outlined in this paper.We point out two possibilities of the existense of pure electric waves and pure magnetic waves; one in coordinate systems satisfying eq. (3) and other conditions discussed in this paper and the, other in problems where some forms of symmetry exist so that the system of Maxwell's equations can be broken into two independent groups, which we also call respectively electric waves and magnetic wavea.By means of the proposed-method some complicated boundry value problems can be solved with ease as we have done here for the problem of the excitation of waveguides by a dipole from the known solution of the corresponding static problem. Since there is a rich accumulation of electrostatic and magnetostatic problems so the method proposed here should be valuable in solving field problem and should be studied further.