Horizontal Pendulum with Variable Modulus of Torsion (Resonance Curve)

Abstract

A didactical apparatus for accurate determination of resonance curves is presented. A bifilarly suspended disk, whose natural period is variable between large limits while the system is oscillating, is suited for easy determination of a resonance curve, because the period of the forced oscillation can remain unchanged during operation. The rigidity and hence the natural period of the pendulum is altered by a change in the mass supported by the bifilar suspension; this is done by means of a third axial wire, from the disk to a yoke carrying counterweights.