Förderverein der Archenhold-Sternwarte
und des Zeiss-Großplanetariums Berlin e.V.

Dr. Jürgen Rose

Foucault’s Pendulum

Frenchman Jean Bernard Léon Foucault (1819-1868) completed a series of experiments with a major demonstration. Using a pendulum, he impressively demonstrated the rotation of the Earth. To the observer, the plane in which the pendulum swings appears to turn slowly. This apparent change, however, is actually attributable to the Earth’s rotation. To be able to show this effect to a greater public, for his demonstration in the Panthéon in Paris in 1851, he used a 28 kg metal ball suspended on a 67 m metal wire. Of course, during Foucault’s time the known laws of physics no longer questioned that the Earth rotated about its axis daily. A convincing experimental demonstration had, however, not previously been accomplished.

Furtherance activities at the Archenhold-Observatory show the functionality of such a pendulum.

Foucault Pendel der AStW
Chart: Nbrouard (Own work) [CC-BY-SA-3.0], via Wikimedia Commons


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