The Hall effect is a phenomenon discovered by Edwin Hall in 1879, which occurs when an electric current flows through a conductive material in the presence of a perpendicular magnetic field. As a result of this interaction, a voltage difference, known as the Hall voltage, is generated across the conductor's width, orthogonal to both the current and magnetic field directions.

The Hall effect arises due to the deflection of charge carriers (electrons in most conductors or holes in semiconductors) by the magnetic field. The charge carriers accumulate on one side of the conductor, creating an electric field that opposes further charge accumulation. When the force exerted by the electric field balances the force from the magnetic field, the Hall voltage reaches a steady state.

Hall effect sensors are devices that exploit this phenomenon to measure magnetic fields, current, or position. These sensors consist of a thin layer of conductive material and are often made from semiconductors like silicon, germanium, or indium antimonide. When a magnetic field is applied perpendicular to the current flowing through the sensor, the Hall voltage is generated, which is proportional to the magnetic field strength.

Hall effect sensors are widely used in various applications, such as measuring the strength and direction of magnetic fields, detecting the presence or position of magnets, and measuring current in current transformers. They are also used in many automotive applications, including wheel speed sensing in anti-lock braking systems (ABS), crankshaft and camshaft position sensing in engine management systems, and throttle position sensing.