Superconductivity is the ability of some materials to conduct electric current without resistance at extremely low temperatures. These materials, called superconductors, have many useful properties. Electric current can flow through a superconductor without loss of energy. Superconductors can also produce powerful magnetic fields, some more than 400,000 times stronger than Earth's magnetic field. A magnetic field is the region around a magnetic object or electric current in which its magnetic force can be detected. The Dutch physicist Heike Kamerlingh Onnes discovered superconductivity in 1911.