Chapter 27 Electromagnetic Induction and faraday's law Introduction After Oersteds discovery in 1820: a steady current produced a steady magnetic field, experimentalists eagerly sought to demonstrate the reverse: a steady magnetic field could create a steady electric current. 1820年丹麦物理学家奥斯特发现了电流的磁效应, 就开始了其逆效应的研究。Chapter 27 Electromagnetic Induction and Faraday’s Law After Oersted’s discovery in 1820: a steady current produced a steady magnetic field, experimentalists eagerly sought to demonstrate the reverse: a steady magnetic field could create a steady electric current. 1820年丹麦物理学家奥斯特发现了电流的磁效应， 就开始了其逆效应的研究。 Introduction