When ordinary AC voltage is applied to a large coil of wire with an iron core, a strong alternating magnetic field is produced. If an aluminum ring is placed over the core and 120 volts AC is connected, a large current is induced in the ring according to Faraday's Law and it is tossed into the air. Note that if the magnetic field on the aluminum ring were perfectly vertical, the magnetic force by the right-hand rule would be radially inward and outward on the ring - and if you hold the ring down, you can hear it hum at 60Hz from that alternating force. But at the location where the magnetic field exits the coil, it diverges and will have radially outward and inward components.The force resulting from those components are upward and downward on the ring. The first upward force pulse will launch the ring into the air. At the end of the video is the contrast with a ring with a slot cut into it so that no circulating induced current is produced.