Test instruments to measure magnetic field strengths are often based on the Hall effect. In one instrument, the “probe” is a 1.0-mm-thick, 6.0-mm-wide semiconductor with a charge-carrier density of 2.1 × 10²¹ m^-3, much less than the charge-carrier density in a conductor. Passing a 60 mA current through the probe generates a Hall voltage of 120 mV. What is the magnetic field strength?