Hall effect

The Hall Effect (discovered by Dr. Edwin Hall in 1879) states that when a [magnetic field]? is applied perpendicular to a thin sheet of conducting or semiconducting material through which current is flowing (the Hall element), a potential (voltage) difference will be created on opposite edges of the hall element. By measuring the Hall voltage across the sensing element, one can determine the strength of the magnetic field applied perpendicular? to the Hall element. Hall Effect Sensors are readily available from a number of different manufacturers. The most common types are Analog Hall Effect Sensors (which output a voltage that is proportional to the applied magnetic field) and Digital Hall Effect Sensors (which are often used as magnetically controlled switches -- they turn on or off when the applied magnetic field reaches a certain level).