Foucault pendulum Foucault pendulum The Foucault pendulum ( ; ) or Foucault's pendulum is a simple device named after French physicist Léon Foucault and conceived as an experiment to demonstrate the Earth's rotation. The pendulum was introduced in 1851 and was the first experiment to give simple, direct evidence of the earth's rotation. Today, Foucault pendulums are popular displays in science museums and universities. The first public exhibition of a Foucault pendulum took place in February 1851 in the Meridian of the Paris Observatory. A few weeks later, Foucault made his most famous pendulum when he suspended a 28-kg brass-coated lead bob
Foucault pendulum vector diagrams the each figure represents the range of swing of the pendulum as viewed from above and normalized to a standard orientation. The smaller arrows depict the magnitude of the relative velocity vector for the point on the Earth's surface in-line with the pendulum bob projected to the center of the Earth (the magnitude is shown since the scematic is two-dimensional, not three-dimensional). The pendulum bob is always affected by the force of gravity directed towards the center of the Earth. The force associated with the connection of the pendulum to a support structure directs the pendulum bob along the swing