This well-known object designed by Jean Bernard Leon Foucault consists of a simple pendulum in which a heavy sphere, attached to a long metallic thread, is allowed to swing in any direction . This oscillatory movement is derived from the force of gravity on the object, which causes it to begin to move, and from the inertia of the body itself once it is in motion until another force opposes it and stops it. In theory, the plane of oscillation of a pendulum should remain fixed in space ; but the rotation of the Earth causes the plane of oscillation to vary.
This fact was corroborated in 1851 by Jean Bernard Leon Foucault (1819-1868), who decided to hang a huge pendulum 68 meters long from the dome of the Pantheon in Paris. In the heavy 30-kilogram sphere at its free end, Foucault placed a fine metal point that left a trace on the sand-covered ground , allowing him to follow its movement clearly and precisely. An hour after the pendulum began to move, the surprised people present observed the pattern that had formed on the ground, showing that the pendulum had “rotated” several degrees from its original trajectory .
This curious experiment would go down in the history of physics as the first experimental proof that the Earth rotates on its own axis with a rotational motion . The oscillation angle of his pendulum was shifted 11º and 15 ‘every hour , but the variation in the oscillation of the pendulum changes according to the latitude in which we are. In this way, at the poles the pendulum completes one revolution every 24 hours and at the equator its trajectory is hardly affected . The hemisphere in which the experiment is performed also affects its result. The original pendulum used by Foucault is currently in the Cleveland Museum of Natural History , in the United States. In addition, there are a large number of Foucault pendulums around the world, because they are simple and attractive objects that many people know and that tend to be interesting for most of the public.
In addition to the one used by its creator, one of the best known is the one found inside the Pantheon in Paris, where the original experiment was carried out , and which imitates the aesthetics of the time in the place where the discovery was made. This 125 kilogram pendulum takes about 6.2 seconds to complete a back and forth movement and, to help counteract minor external forces such as air resistance or cable friction, a system of electromagnetic magnets was designed to counteract these forces. without actually interfering with the natural movement of the pendulum .
