Can static electricity make a metal tab swing back and forth between two soda cans? Benjamin Franklin built a version of this device to detect approaching lightning storms.
You hang a pull-tab from a thread between two empty soda cans. One can connects to an electrical ground. The other connects to a source of static charge, such as aluminum foil placed on an old CRT screen.
The charged can repels the tab toward the grounded can. The tab dumps its charge and swings back. This cycle repeats several times per second. Occasional sparks snap between the cans.
Hypothesis
The hypothesis is that a high voltage motor can be built with everyday items.
A pull-tab hanging from a thread between two soda cans can swing back and forth on its own — powered entirely by static charge. One can connects to an electrical ground; the other connects to a source of static charge, such as aluminum foil placed on an old CRT screen. The charged can repels the tab toward the grounded can, where the tab dumps its charge on contact and swings back. This cycle repeats several times per second, and occasional sparks snap between the cans. Benjamin Franklin built a version of this same device to detect approaching lightning storms.
Electrostatic discharge does not always happen as a single spark — it can repeat in a rapid cycle. When a charged soda can repels a metal tab toward a grounded can, the tab dumps its built-up charge on contact and swings back to collect more. This back-and-forth cycle repeats several times per second, and occasional sparks snap between the cans as the charge jumps across the gap.
Method & Materials
You will need to remove the pull-tops from two soda cans, tie a thread to one of the pull-tops, tape the other end of the thread to a plastic rod, place the two cans side-by-side, tape one wire to the left can and the other wire to the right can.
You will need two empty soda cans, a plastic rod, 5 inches of sewing thread, aluminum foil, cellophane tape, and two wires.
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The experiment showed that a high voltage motor can be built with everyday items. The motor acts like a bell, with a clapper that bangs furiously from one can to the other and back again. The big blue spark that snaps between the cans adds to the frenetic activity.
Why do this project?
This science project is unique because it is so simple to build and it only takes 5 minutes to put together.
Also Consider
Experiment variations to consider include using different materials for the cans, such as metal cans, or using different materials for the plastic rod, such as a wooden dowel.
Full project details
Additional information and source material for this project are available below.
