A copper strip (n = 8.47 × 1022 electrons per cubic centimeter) 2 cm wide and 0.1 cm thick is used to measure the magnitudes of unknown magnetic fields that are perpendicular to the strip. Find the magnitude of B when I = 20 A and the Hall voltage is

(a) 2.00 μV,

(b) 5.25 μV, and

(c) 8.00 μV.