The electric motor uses the principle of the force of the energized conductor in the magnetic field (this is different from the current of the magnetic effect of the theory, the current version of the nine-year physics clearly separate the two), found that the principle of the Danish physicist-Ost, August 14, 1777 born in Langlan Islandiobine, a pharmacist family. He entered the University of Copenhagen in 1794 and received his doctorate in 1799. 1801-1803 years to Germany, France and other countries visit, met a lot of physicists and chemists. He was a professor of physics at the University of Copenhagen in 1806 and the Permanent Secretary of the Royal Society of Denmark since 1815. The Copley Medal of the Royal Society was awarded in 1820 for the remarkable discovery of the current-magnetic effect.