Hall effect sensor
A Hall effect sensor (also known as a Hall sensor or Hall probe) is any sensor based on the Hall effect (named after physicist Edwin Hall), in which a voltage is produced proportional to one axial component of the magnetic field vector B. Hall sensors are used for proximity sensing, positioning, speed detection, and current sensing applications and are common in industrial and consumer applications. Hundreds of millions of Hall sensor integrated circuits (ICs) are sold each year by about 50 manufacturers, with the global market being valued at around a billion dollars.