Maxwell’s equations could not explain the zero resistance and perfect diamagnetism observed as main characteristics of superconductivity. F. London and H. London (London brothers) suggested that motion of superconducting electrons in the presence of applied electric field E. If a magnetic field is applied to a superconductor which is initially in zero field, the magnetic field is a function of time. The potential decay of magnetic field at the interior surface of superconductor. Mathematical expression for the Hall voltage is given by: Bx = B0 e- xλ Where, B0 = magnetic field at the surface Where, x = distance inside the superconductor from surface Where, λL = Penetration depth The potential decay of magnetic field at the interior surface of superconductor. λL is the distance across which the magnetic field becomes ' e ' times weaker. λL can be formulated as: λL = mμ0 n q2 Where, m = charge carrier of mass Where, n = number of density Where, μ0 = absolute permeability
