圆电磁学0801：电磁感应实验现象 Some movies for demonstration Back emf in a Large Solenoid Galvanometer Principle Jacob's Ladder and the Melting Nail Lenz's Law Pendulum and Magnet电磁学08-01: 电磁感应实验现象  Some movies for demonstration  Back emf in a Large Solenoid  Galvanometer Principle  Jacob's Ladder and the Melting Nail  Lenz's Law  Pendulum and Magnet