This entry contributed by Roger Carr

When electrons (or holes) move in a conducting plate that is immersed in a magnetic field, they experience a Lorentz force

(1)

(in MKS), where q is the charge, E is the electric field, v is the velocity, and B is the magnetic field. Note that the second term is transverse to velocity and to the magnetic field. Therefore, if sensing electrodes are placed across the transverse dimension of the plate, a voltage, called the Hall voltage, will appear.

Hall Voltage, Quantum Hall Effect