Hall effect

In diagram A, the flat conductor possesses a negative charge on the top (symbolized by the blue color) and a positive charge on the bottom (red color). In B and C, the direction of the electrical and the magnetic fields are changed respectively which switches the polarity of the charges around. In D, both fields change direction simultaneously which results in the same polarity as in diagram A. electrons flat conductor, which serves as a Hall element (Hall effect sensor) magnet magnetic field power source

The Hall effect is the production of a potential difference, across an electrical conductor, that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. Such potential difference is known as the Hall voltage. It was discovered by Edwin Hall in 1879 through a study of the electromagnetic theory of James Clerk Maxwell, becoming a critical confirmation of that theory.