A 0.70-m aluminum bar is held with its length parallel to theeast-west direction and dropped from a bridge. Just before the barhits the river below, its speed is 29 m/s, and the emf inducedacross its length is 7.0 x 10-4 V. Assuming thehorizontal component of the Earth's magnetic field at the locationof the bar points directly north, (a) determinethe magnitude of the horizontal component of the Earth's magneticfield, and (b) state whether the east end or thewest end of the bar is positive.
