Oersted, Hans Christian (1777-1851), a Danish physicist and chemist. His investigations laid the foundation for the science of electromagnetism. In 1820 Oersted observed that a magnetic needle could be deflected by an electric current. This led him to conclude that there was a fundamental relationship between electricity and magnetism. In 1825 he was the first to isolate aluminum (in an impure form). He taught at the University of Copenhagen, 1806-29. He became the first director of the Polytekniske Laereanstalt (the Danish technical institute) in 1829.