Hall effect is a kind of electromagnetic effect, this phenomenon is the physicist hall (A.H.H all, 1855-1938) in 1879, found in the research on the conductive mechanism of metal. When the current is perpendicular to the magnetic field through the conductor, in parallel to the direction of the magnetic field and electric current in a conductor will be potential difference between two end face, this phenomenon is called the hall effect. The electric potential difference, also known as the hall electric potential difference. Hall effect should use left hand rule judgment