Video narration
How can a magnet slow a metal wheel without ever touching it? You know magnets attract or repel metal. But a moving magnet near conductive metal creates resistance, like dragging your hand through water: faster motion brings stronger drag. Here's the flip: the metal is not passive. As the magnet moves, its changing field drives electric currents into loops inside the metal, not through an outside wire. These are eddy currents. Those loops create a magnetic field that opposes the change, pushing back against the magnet's motion. That produces braking force, and turns some motion energy into heat. That's useful in contactless magnetic brakes, and in induction cooktops, where the same effect heats cookware. So how does the magnet slow the wheel without touching it? The moving magnet creates eddy currents in the metal; their opposing field produces touch-free drag.