D.E.V.I.C.E. is an encyclopedia of terms used by manufacturers of test and measurement equipment. T&M Atlantic created this service to better explain the functionality of instruments it offers, and to highlight the latest developments in the world of measurement equipment. We are using such tools as animation to bring words and pictures to life and to create not just an understanding but also an appreciation for technology that goes into the design of every instrument.
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A Hall probe contains an indium compound semiconductor crystal such as indium antimonide, mounted on an aluminum backing plate, and encapsulated in the probe head. The plane of the crystal is perpendicular to the probe handle. Connecting leads from the crystal are brought down through the handle to the circuit box.
When the Hall probe is held so that the magnetic field lines are passing at right angles through the sensor of the probe, the meter gives a reading of the value of magnetic flux density (B). A current is passed through the crystal which, when placed in a magnetic field has a "Hall effect" voltage developed across it. The Hall effect is seen when a conductor is passed through a uniform magnetic field. The natural electron drift of the charge carriers causes the magnetic field to apply a Lorentz force (the force exerted on a charged particle in an electromagnetic field) to these charge carriers. The result is what is seen as a charge separation, with a buildup of either positive or negative charges on the bottom or on the top of the plate. The crystal measures 5 mm square. The probe handle, being made of a non-ferrous material, has no disturbing effect on the field.