Challenge: To create the longest spark possible.
Parameters: You will have to build an electrostatic generator with found materials. You will provide the work, through friction and the triboelectric effect, to build up static charge on your device. It must discharge to a grounding object a measurable distance away, while being recorded by slow-motion video in a darkened area.
Scoring: You will be evaluated based on the voltage produced by your generator, as measured by the length of the sparks generated.
Score = Length of Spark in millimetres
If we assume dry air, which breaks down (ionizes) at an electric field strength of 3000 V/mm or 3000 mN/C, we can estimate the voltage of your device, and the strength of the electric field it produces.
Rank will be based on score, with highest score earning highest rank.
Physics: Materials with different affinity for electrons, when rubbed together, may transfer electrons and therefore build up opposite charge. If you can keep the charges from dissipating or flowing to ground (ie a static charge), a large voltage can be developed across an insulator like air. If high enough field strength is developed (by building up more static charge, or deforming your storage material, or moving a grounded object closer), a spark will occur as the air ionizes and the charges flow all at once to ground.
Extensions: The materials you use matter. Ideally they are far apart on the triboelectric series. Storing up charge is difficult. Like charges repel each other! Think about the shape of the van Der Graf generator. Look up capacitors and dielectric constants. Research Leyden jars, Wimshurst generators, etc. etc.
Help/Hints: Give yourself time for iteration. If you can make a spark reliably try changing one thing at a time to see what can make it better.
Quiz Topics: Electric charge, Coulomb’s Law, electric fields, electric potential energy, voltage, capacitance
Online Text: 18.1-18.5 (with math), 18.6-18.8 (no math), 19.1-19.7