London theory of superconductivity

The London theory explains how superconductors conduct electricity without resistance by describing how magnetic fields behave within them. It proposes that in a superconductor, magnetic fields are expelled or confined near its surface, a phenomenon called the Meissner effect. This occurs because supercurrents create magnetic fields that cancel external ones inside the material. The theory models these behaviors using equations that relate current and magnetic fields, emphasizing that in a superconductor, the electromagnetic properties change drastically, allowing perfect conductivity. While it doesn't explain the underlying atomic or quantum mechanisms, the London theory provides a foundational understanding of the electromagnetic aspects of superconductivity.