Michael Faraday unsuccessfully attempted to measure the potential difference across the River Thames due to the flow of water (which is a good conductor due to dissolved salts) in the earth's field. At Waterloo Bridge, where Faraday made his attempt, the river is \(200 \mathrm{~m}\) wide and flows eastward at \(2.0 \mathrm{~m} / \mathrm{s}\). The earth's magnetic field here has a magnitude of \(50 \mu \mathrm{T}\) and is tipped \(65^{\circ}\) from the horizontal, so it has both horizontal (north) and vertical (down) components. Is the north or south riverbank at a higher potential? What is the magnitude of the potential difference?