Electric current certain materials when cooled below a characteristic critical temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of "perfect conductivity" in classical physics. In a semiconductor it is sometimes useful to think of the current as due to the flow
1732 Heike November 1977 (). 1732 Heike 1732 Heike, provisional designation , is a stony Eoan asteroid from the outer region of the asteroid belt, approximately 24 kilometers in diameter. It was discovered on 9 March 1943, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany, and named after Heike Neckel, the granddaughter of astronomer Alfred Bohrmann. The S-type asteroid is a member of the Eos family. It orbits the Sun in the outer main-belt at a distance of 2.7–3.3 AU once every 5 years and 3 months (1,911 days). Its orbit has an eccentricity of 0.11 and an inclination