A Hall effect sensor is any sensor incorporating one or more Hall elements, each of which produces a voltage proportional to one axial component of the magnetic field vector B using the Hall effect.
Engine fan with Hall effect sensor
Hall effect current sensor with internal integrated circuit amplifier. 8 mm opening. Zero current output voltage is midway between the supply voltages that maintain a 4 to 8-volt differential. The non-zero current response is proportional to the voltage supplied and is linear to 60 amperes for this particular (25 A) device.
Diagram of Hall effect current transducer integrated into ferrite ring
Multiple 'turns' and corresponding transfer function
Edwin Herbert Hall was an American physicist, who discovered the electric field Hall effect. Hall conducted thermoelectric research and also wrote numerous physics textbooks and laboratory manuals.
Edwin Herbert Hall (1855-1938)