The Hall Effect
The Hall effect (named after the American physicist Edwin Herbert Hall, 1855-1938) discovered in 1879, is the basis for all Hall-effect devices. It involves the generation of an electric potential perpendicular to both an electric current flowing along a conducting material and an external magnetic field applied at right angles to the current upon application of the magnetic field.
Where: B = applied field, I = input current and VH= Hall voltage
The Hall element, produces an output voltage proportional to a magnetic field or to the distance between a magnet and the sensor. To make a linear magnetic sensor, this small voltage is processed through a high-quality amplifier, which produces an analog output that is proportional to the applied flux density.