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Abstract
The Coulomb barrier is a classic introductory physics concept and one that is key to understanding nuclear fusion. Yet the idea that fusing atoms could exhibit both far-range repulsion and short-range attraction can result in significant cognitive dissonance in students. There are no classical examples of this behavior and no commercially available demonstration kits. The magnetic potential energy barrier apparatus allows a visual and tactile demonstration of repulsion at a distance and strong short-range attraction. Students directly experience the role of kinetic energy in overcoming a potential energy barrier.
Supplementary materials
Title
Magnetic "Coulomb" barrier video abstract
Description
A pair of magnet arrays each containing a series of alternating/unequal magnets demonstrates repulsion at a distance and attraction at close range. This models the behavior of the Coulomb barrier.
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Title
Materials list and force/distance data between a pair of magnetic "Coulomb" barrier arrays
Description
This spreadsheet contains raw data and materials list.
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Supplementary weblinks
Title
3D print file, top magnet array housing, 1 of 2
Description
Alternating single and double 3/8" N52 Nd cylinder magnets (9 total) are placed within this housing (see pictures), centered by an aluminum inline skate spacer 23.5mm x 7.9 mm, 6.3 mm ID that acts as a plain bearing and slides over a 6mm rod (Hoppes .308 gun cleaning rod works well).
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3D print file, bottom magnet array housing, 2 of 2
Description
Alternating single and double 3/8" N52 Nd cylinder magnets (9 total) are placed within this plastic housing (see pictures). The housing accommodates a 22mm x 7mm ceramic bearing with 8mm ID that fits an aluminum inline skate bearing spacer (23.5mm x 7.9 mm, 6.3 mm ID) secured to a base and centered around a 6mm rod (Hoppes .308 gun cleaning rod works well).
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