Test instrument 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 2.1x 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?
The Hall voltage is given by
where is current,
is magnetic field,
is charge-carrier density,
is charge of electron,
is thickness of the "probe"
Then:
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