In order to identify the movement of water in the ocean, oceanographers at times rely on the motional emf produced by the movement of the water via the magnetic field of the Earth. Assume that, at a place where the vertical magnetic field is around 7.0x10^-5 T, the two electrodes are immersed in the water separated by a distance of 200 m measured perpendicularly to the movement of the water. When a sensitive voltmeter joined to the electrodes points out a potential difference of around 7.0x10^-3 V, determine the speed of the water?