Ring Launcher Model

Quick Answer: The Ring Launcher Model is a jumping-ring demonstration in which a coil wound around a long iron core throws a conducting ring up the core when the current is switched on. It is used in physics lessons on electromagnetic induction, eddy currents and Lenz’s law.

Why the Ring Jumps

The listing image of the ring launcher model shows a boxed base with a tall metal core standing out of the top and a power cable at the side. Inside the base a coil surrounds the lower end of the core. A light conducting ring, usually aluminium, is dropped over the core so that it rests on top of the base. When alternating current flows in the coil, the iron core carries a rapidly changing magnetic field up through the ring.

That changing magnetic flux induces a current around the ring. By Lenz’s law, the induced current flows in the direction that opposes the change producing it, so the ring behaves like a small magnet facing the coil with like poles together. The repulsion throws the ring up the core. With the current left on, a ring can instead float at a steady height, where the magnetic push balances its weight, and it warms noticeably because the induced current heats it.

Simple variations make the lesson memorable: a ring with a saw cut through it does not move because no current can circulate around it, a plastic ring does nothing at all, and a ring cooled in iced water flies a little higher because its lower resistance lets a larger current flow. Whether the unit runs from mains or from a low-voltage AC supply, and which rings are included, should be checked before ordering.

Specifications

Lessons It Supports

• Introducing electromagnetic induction with an effect students can see from the back of the room
• Demonstrating Lenz’s law by comparing a solid ring with a split ring
• Showing induced heating by letting a ring hover and then noting that it has warmed
• Linking to transformers, induction hobs and magnetic braking

Care & Handling

• Switch the ring launcher model on only in short bursts; the coil heats up under continuous current.
• Stand to one side rather than leaning over the core, because the ring leaves the top at speed.
• Let a hovering ring cool before handling it, and use tongs if it has been floating for more than a few seconds.
• Keep the power cable and plug in good condition, and unplug the base when it is not in use.

Why Choose LabEquip

Physics teachers often choose a jumping ring to open a unit on induction because it makes an abstract law visible in seconds. LabEquip lists the ring launcher in its STEM kits range, and the Solenoid Working Model is a useful companion for showing the magnetic field of a coil before the ring is introduced. Ask about supply options through the contact page.

Frequently Asked Questions

Why does a split ring not jump?

The cut breaks the conducting path, so an emf is still induced but no current can flow around the ring. Without current there is no opposing magnetic field and no force. This comparison is the clearest way to show that the induced current, not the metal itself, causes the jump.

Will the ring jump if the coil is connected to DC?

Only once, at the moment the current is switched on, because that is the only time the flux changes. A steady direct current produces a constant field and induces nothing. An alternating supply keeps the field changing, so the ring can be thrown or held hovering.

What is the ring made of, and can other materials be tried?

Aluminium is the usual choice because it conducts well and is light. A copper ring conducts even better but is heavier, a brass ring conducts less well, and a plastic ring does not respond at all. Trying rings of different metals shows how conductivity and mass both matter.

Why does a hovering ring get hot?

The induced current flows around the ring continuously, and the ring’s resistance turns that electrical energy into heat. It is the same effect that heats a pan on an induction hob. Do not leave a ring floating for long, and handle it with care afterwards.

Is the demonstration safe for a classroom?

Yes, when the teacher operates it. Keep students at a short distance, never place a hand over the core when switching on, use brief pulses of current and switch off at the wall afterwards. Anyone with an implanted medical device should stay back from strong changing magnetic fields.

How does the ring launcher relate to real technology?

The coil and ring form a simple transformer whose secondary is a single shorted turn. The same repulsion idea is used in electromagnetic launch systems, and the eddy currents involved also drive induction heating and the magnetic brakes on some trains and rides.

Last Updated: September 2026