Our Lenz’s Law apparatus is a simple and effective way to demonstrate induction and Lenz’s Law of electrodynamics. The metal hoops (one open and one closed) are freely moving on a centrally mounted pin. When a magnetic field is introduced to the closed loop from a bar magnet, an electrical current and a magnetic field are created that will repel against the original magnetic field. This is demonstrated when the loop moves away from the approaching magnet. Alternately, when you approach the open loop on the left with a bar magnet, nothing will happen.