The interaction of electromagnetic radiation with a time-switched magnetoplasma is considered. Exact analysis, including ion motion, for longitudinal propagation is given. The original wave splits into four new waves whose frequencies are different from the incident wave frequency. Approximate dispersion relations are obtained in the Alfv¿n and hydromagnetic ranges. The energy distribution, power content, and frequency shifts in each of the four new waves are discussed in these low-frequency regions. It is shown that the low-frequency waves degenerate into dc wiggler magnetic fields for the limiting case of switching an isotropic plasma medium. Parameters and typical values for an experiment that will illustrate the generation of new waves are given. ¿ American Geophysical Union 1993