Magnetic flow meters use Faraday induction to produce a voltage across a channel in which a conductive fluid is flowing. The basic relationship (using convenient geometry so that the cross products simplify) is
Voltage = k･v･B･L
where k is a calibration constant, v is the fluid flow speed, B is the constant external magnetic field strength and L is the distance across the channel.
My first question is, other than specifics of the electronic design and exact instrument configuration, how does the constant k depend on the conductivity of the fluid? How does one calculate the effective charge and current densities? I am particularly interested in seawater as the conducting fluid.
Secondly, given a voltage set up between the electrodes, presumably work can be down by connecting the output to a load. The situation I am envisioning is that the EMF set up by the flow through a magnetic field will be aligned along a conducting cable (oriented in the appropriate direction, of course). However, I am concerned about internal resistance of the cable "robbing" the available energy of the system. Can you explain how this set up would work (or not!)?
