This paper deals with a system of equations describing the motion of viscous electrically conducting incompressible fluid in a bounded three dimensional domain whose boundary is perfectly conducting. The displacement current appearing in Maxwell's equations, $\epsilon E_t$ is not neglected. It is proved that for a small periodic force and small positive #\epsilon# there exists a locally unique periodic solution of the investigated system. For $\epsilon \rightarrow 0$, these solutions are shown to convergeto a solution of the simplified (and usually considered) system of equations of magnetohydrodynamics.
 N. G. Van Kampen B. U. Felderhof: Theoretical Methods in Plasma Physics. North-Holland Publishing Company - Amsterdam, 1967.