Lenz's Law Demonstration Tube — Magnetic Braking in a Copper Tube

Drop a magnet through a copper tube. Watch it fall in slow motion — stopped by a force with no moving parts.

This is Lenz's law in its purest form. As the magnet falls through the non-magnetic copper tube, it induces eddy currents that create an opposing magnetic field — slowing the magnet to a fraction of gravitational speed. There is no friction, no mechanism, just electromagnetic induction acting at a distance through the metal wall.

What you can demonstrate:

• Faraday's law of electromagnetic induction
• Lenz's law — induced currents oppose their cause
• Eddy currents in conductors
• The connection between changing magnetic flux and electric current
• Why MRI machines use superconducting coils to maintain field stability

Includes: Thick-wall copper tube (30cm) · Matched neodymium magnet (same diameter as tube bore) · Identical steel slug for comparison · Stand

Drop both at once: the steel slug falls instantly; the magnet floats down in 10 seconds. The room always goes quiet.