# Gaussmeter

You'd use gaussmeter to measure field strengths—to determine the extent of the fringe field, for example. A gaussmeter relies on the Hall effect. If an electric current (I) flows through a flat conductor in a magnetic field, the magnetic field exerts a transverse force on the moving charge carriers which tends to push them to one side of the conductor. By measuring voltage produced (the Hall voltage V_{H}), the magnetic field strength (B) can be calculated using

V_{H} = IB / net,

where n = the number density of charge carriers, e = electron charge and t = thickness of the flat conductor.