Foucault pendulum with eddy‐current damping of the elliptical motion
| Autor: | G. Mastner, H. P. Kaufmann, V. Vokurka, E. Vogt, M. Maschek |
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| Rok vydání: | 1984 |
| Předmět: | |
| Zdroj: | Review of Scientific Instruments. 55:1533-1538 |
| ISSN: | 1089-7623 0034-6748 |
| Popis: | A newly designed Foucault pendulum is described in which the mechanical Charron ring, used throughout in previous designs for damping of the elliptical motion of the pendulum, is replaced by an electromagnetic eddy‐current brake, consisting of a permanent magnet attached to the bottom of the bob and a metallic ring. This damping device is very efficient, as it is self‐aligning, symmetrical in the damping effect, and never wears out. The permanent magnet is also used, together with a coil assembly and an electronic circuitry, for the dipole‐torque drive of the pendulum as well as for accurate stabilization of the amplitude of the swing. A latched time display, controlled by Hall probes activated by the magnet, is used to visualize the Foucault rotation. The pendulum system and its associated electronic circuitry are described in detail. The optimizing of the drive mode is discussed. Measurements of deviations from theoretical value of the Foucault rotation velocity made automatically in a continuous run show a reproducible accuracy of ±1% or better in individual 360° rotations during the summer months. The quality factor of the pendulum as mechanical resonator was measured as a function of the amplitude in the presence of the eddy‐current damping ring. |
| Databáze: | OpenAIRE |
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