Here we have a ring thrower, ring shooter, jumping ring, repulsion coil, etc, it may have many names but the effect is the same - an induced current in a closed conducting ring will opposes any change in the source that produced it - or this device will shoot an aluminum ring several feet straight up (or does the ring shoot itself?). It provides excitement, amazement and curiosity, a great item for science centers, schools and makes a unique gift.
This repulsion coil has 2 modes of operation, the first mode is the shoot mode and it is fully adjustable, the jumping ring can be adjusted to shoot from 1 inch to over 8 feet and will jump consistently to set levels, the level can be adjusted so that the ring stays on the supplied 5' fiberglass rod, this helps in demonstrations where you need repeatability and don't want to chase a ring around the room, or have it ricocheting off the ceiling and damaging something. The repulsion coils second mode is the hover mode and the ring can be adjusted to hover from 1/8" to approximately 6", this can be used to demonstrate a form of magnetic levitation.
The repulsion coil is precision controlled and regulated, it will run off a standard 120 vac 60 cycle wall outlet (no special power requirements needed).
So where's the science you ask?
This device is an excellent demonstration of Lenz's law, and several methods to test and confirm his writings.
Heinrich Emil Lenz (1804-1865) further explained Faraday's Law when he formulated Lenz's law in 1834 which states that "the emf induced in an electric circuit always acts in such a direction that the current it drives around a closed circuit produces a magnetic field which opposes the change in magnetic flux."
The main tube is made of stainless steel wrapped in carbon fiber, capped with a black Delrin ring guide / rod holder and a white 5 foot fiberglass rod. The wood is solid red oak finished in polyurethane, all exposed hardware is stainless steel and the unit is supplied with a 6 foot ac cord.