The testing of small specimens of soft magnetic materials

Specimens weighing 10g or less and carrying easily wound coils about 20 turns can be used for measuring magnetic properties. The small signals from these low-inductance specimens are easier to handle if they are alternating rather than direct current. Bridge networks adapted to measure low impedances are recommended for measuring permeability and loss, at either low or high flux densities and at frequencies up to 10Mc/s. Coercivity, remanence and saturation can be measured by subjecting specimens to pulses superimposed on various values of bias and integrating the resulting signals. Appendices discuss the choice of series or parallel circuits to represent loss in a magnetic material, and methods of measuring the time-integral of a signal.