Lenz’s Law Visualizers

An open-source hardware initiative by OpenApparatus

This repository began with the dual-tube Lenz’s Law visualizer and now includes multiple design variations for demonstrating eddy currents and magnetic braking in physics classrooms. Each design has its own version history, printable parts, images, materials list, and assembly instructions.

Choose a design

Design	Published version	Description	Build guide and files
Dual-tube	v1	Compare a magnet descending through copper tube with a control weight falling through a clear tube.	View dual-tube design
Triple-tube	v1	Compare a control weight in a clear tube with magnets descending through aluminum and copper tubes; the control falls fastest and the copper-tube magnet slowest.	View triple-tube design
See-through	v1	Watch a ring magnet and a nonmagnetic control ring descend around matching copper tubes inside clear tubes, making magnetic braking directly visible.	View see-through design

Dual-tube visualizer

The dual-tube design’s build guide includes materials, printing settings, assembly instructions, safety notes, deployment evidence, and stress-test information. Download the end-cap STL and the optional control-weight STL directly.

Triple-tube visualizer

The triple-tube v1 build guide includes materials, printing settings, assembly instructions, safety notes, a prototype photograph, and printable parts. This variation adds an aluminum tube alongside the copper and clear tubes, allowing a qualitative comparison of magnetic braking in the two conductive-tube assemblies. It reuses components from the dual-tube design wherever practical.

See-through visualizer

The see-through v1 build guide includes materials, printing settings, assembly instructions, safety notes, a prototype photograph, and printable parts. This design places a ring magnet and a printed control ring around matching copper tubes, with clear outer tubes keeping both descents visible.

Repository layout

README.md                       Overview and design comparison
CITATION.cff                   Citation metadata for GitHub
LICENSE                         Shared hardware license
designs/
   dual-tube-design/
     README.md                  Existing design’s build guide
     parts/                     Printable STL files
     images/                    Prototype photograph
   triple-tube-design/
     README.md                  v1 build guide
     parts/                     Printable STL files
     images/                    Prototype photograph
   see-through-design/
     README.md                  v1 build guide
     parts/                     Printable STL files
     images/                    Prototype photograph

Citation

Use GitHub’s Cite this repository menu to copy an APA or BibTeX citation generated from CITATION.cff. When citing a particular build, also name the design and version used, such as Dual-Tube Design, v1, Triple-Tube Design, v1, or See-Through Design, v1.

Suggested general citation:

Liu, Jonathan. Lenz’s Law Visualizers. OpenApparatus, 2026. https://github.com/jsxliu/lenz-law-visualizer.

License and attribution

Licensed under the CERN Open Hardware Licence Version 2 – Weakly Reciprocal (CERN-OHL-W-2.0).

Created by Jonathan Liu. If you build from or adapt this project, please preserve attribution and clearly indicate your modifications.

AI assistance and acknowledgements

AI tools assisted with drafting, editing, and organizing this repository’s documentation, including Markdown formatting and educational explanations. Hardware design and build decisions remain under the direction of Jonathan Liu at OpenApparatus, who retains responsibility for the designs, testing, and published documentation.

Get involved with OpenApparatus

• Educators: Request a Beta-Test Donation.
• Students: Apply to Start a Chapter.
• Learn more: Visit openapparatus.org.