In an experiment designed to measure the Earth's magnetic field using the Hall effect, a copper bar 0.410 cm thick is positioned
along an east–west direction. Assume n = 8.46 × 1028 electrons/m3 and the plane of the bar is rotated to be perpendicular to the direction of B. If a current of 8.00 A in the conductor results in a Hall voltage of 4.75 10-12 V, what is the magnitude of the Earth's magnetic field at this location?