Lenz's Law - Permanent Magnet And Coils


To demonstrate Lenz's law in a simple and direct way.


Stand with one-turn and five-turn coils, horseshoe magnet.





Thrust one pole of a strong horseshoe magnet into a coil, or quickly withdraw it from inside the coil. A current is induced in the coil that opposes the motion of the magnet, and the reaction force on the coil results in the coil being either pushed or pulled in the same direction that the magnet was moved. Disconnect the hook for the single turn coil. No current can flow so no force is created.


Thomas D. Miner, Lenz's Law Demonstration, TPT 6, 427 (1968). Don Kangas and Haym Kruglak, Lenz's Law Demonstration, TPT 27, 50 (1989).