The liquid, conductive measured medium flows through a pipe section at flow velocity v, in which a constant magnetic field B is created via 2 solenoid coils M. The 2 solenoid coils M are each arranged on the outside of the pipe, opposite to one another. A voltage in accordance with Faraday's law is induced between electrodes E1 and E2, on account of magnetic field M and the flow of a conductive medium. The voltage is proportional to the flow velocity and is thus proportional to the flow rate. A measured value transducer amplifies the signal and converts it to a standard signal (e.g. 4 - 20 mA).