IYPT 1990, Задачи на турнира — Задача 9. Franklin’s wheel

Problems for the 3rd International Young Physicists’ Tournament

Critical edition

Olympiets Youth Center, Moscow, Soviet Union; June 7‒14, 1990 [1]

Critical edition: translated, restored, and commented text [2]

FINAL DRAFT. — Please do not re-publish. Suggestions and criticism welcome

Translated, edited and commented by Ilya Martchenko. The original edition’s historical notes, sources and acknowledgments are retained with problem 1.

Епиграф

Victories do not attract him.
For him growth means: profound defeat
at the hands of ever greater adversaries.
R. M. Rilke [3]

Условие

Rotation of a little metal bar with pointed spearheads in a well-known “Franklin’s wheel experiment” is explained by the existence of “electric wind”. Explain why the wheel rotates if one places it between the plates of a parallel-plate capacitor and charges the capacitor with an electrostatic generator. If the Franklin’s wheel is replaced with a dielectric disk, will such a disk rotate between the plates of a parallel-plate capacitor charged with an electrostatic generator?

Решение

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Оригинал в Архива: 1990.pdf