FOUCAULT'S PENDULUM

	Foucault in Pantheon, Paris	In the middle of beautiful entrance hall of the Steno Museum you can see a version of the French physicist, Léon Foucault's (1819-68) famous pendulum experiment. With this experiment Foucault in 1851 demonstrated, in a simple and elegant way, that the earth is actually turning on its axis. Thus he con-firmed experimentally a theory having existed for a couple of centuries. Before that it was believed that the entire universe was moving round the earth at rest. Foucault's first laboratory experiment was carried out with a pendulum of 2 metres, and after that he gave an imposing demonstration with a pendulum of 67 metres in the Panthéon in Paris. The pendulum in the Steno Museum is only 11 metres. On the other hand, it is kept going by magnetic impulses from a spool in the floor, enabling it to swing perpetually. The explanation of the experiment is that a freely suspended pendulum will swing constantly on the same level. However, the globe id turning on its axis below the pendulum, and as we are following the rotation, it looks as if the pendulum is moving. If the experiment takes place at the North Pole, a whole revolution will take 24 hours. The nearer you get to the Equator, the longer will one revolution take. At the latitude of Aarhus one revolution will take about 29 hours. Exactly on the Equator it will take an endless time, i.e. there is no rotation. LINKS to more information on Foucault's pendulum Department of Physics, University of Guelph Australian Broadcasting Corporation Encyclopedia Smithsonian The California Academy of Sciences University of Louisville