MSU Physics Professor Alfred Leitner describes the energy gap in superconductors and an experiment used to measure it. The film looks at measurements indicating the disappearance of electrical resistance in the transition to the superconducting state and considers the temperature of transition, the exclusion of magnetic flux (Meissner effect), shielding currents, the "floating magnet," and persistent currents. Includes a discussion of the tunnel effect in connection with experiments involving an electron tunneling junction.