This experimental study separates the hysteresis, eddy current, and electromechanical motion losses of a soft magnetic material for electric power energy conversion applications. Mechanical responses of the magnetic material to sine and square wave voltage excitation are compared. Commercially available, METGLAS 260553-A tape cores were evaluated up to 300/spl deg/C for sine wave and square wave voltage excitation frequencies 1-100 kHz. Data presented illustrates the effects of maximum flux density, frequency, waveshape, and temperature on the specific core loss and size and shape of the B-H loops. Relative losses play a major role in material selection for electronic and electric power applications including power converters, transformers, controllers, and filter elements. Dynamic measurements of the magnetostrictive response of these specific toroidal test cores were made using a sensitive, capacitive probe and a unique application of frequency modulation. The dynamic behavior of the toroidal test cores and the related unusual B-H loop characteristics were compared to results obtained by an electromechanical model. >