Lenz’s law with neodymium magnet + aluminum ingot is revealed. This explains the “UNKNOWN MYSTERY” videos that people have done with hard drive platters and magnets.
Currents bound inside the atoms of strong magnets can create counter-rotating currents in a copper or aluminum pipe. This is done by dropping the magnet through the pipe. When done, the descent of the magnet is observably slower than when dropped outside the pipe.
When an emf is generated by a change in magnetic flux according to Faraday’s Law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it. The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant. In the examples below, if the B field is increasing, the induced field acts in opposition to it. If it is decreasing, the induced field acts in the direction of the applied field to try to keep it constant.
