Abstract: Flow rate of an electrically conductive medium flowing through an electrically insulating pipe section is measured as a function of electrical voltages induced in the medium by electromagnetic fields generated by an exciter coil energized by a pulsating direct current. To eliminate noise signal components the repetition rate of the pulsating direct current applied to the exciter coil is set as an even integer multiple of a frequency of alternating current interference voltage component and the detection of measuring signals occurs in adjustable pick-up intervals of equal length so that a group of four or an integer multiple of four is detected during each period pertaining to the frequency of the interference voltage. Then every second detected measuring voltage is reversed in polarity and thereafter the measuring voltages in each group are integrated whereby the noise components are neutralized and a sum of pure useful voltage components is obtained.