Pendolo di Foucault in miniatura da esposizione
A 3.5-meter long Foucault pendulum is realized for teaching and exhibition purposes. The pendulum operates continuously without need for maintenance or external control. The decay of the oscillation amplitude due to friction is compensated by the application of a pulsed central magnetic force, synchronously activated by means of optoelectronic devices. Effects of asymmetries in the system, resulting in the precession due to the ellipticity of the oscillatory motion, are minimized by the use of a Charron ring below the suspension point of the pendulum wire. A circle of LED diodes, lighting in sequence as the rotation of the oscillation plane progresses, provides a visual observation of the phenomenon. The average rotation period of the plane is only 1,5% short of the theoretical value in Rome (35.96 hours): this proves that the corrections introduced to counteract energy loss and precession do not prevent a satisfactory demonstration of the Earth rotation.