Forced Rotational Oscillations – Stopclock

Free rotational oscillations- measuring with a hand held stop clock. This apparatus can be ordered as a complete set or individually for use with equipment your laboratory may already have. To select products for this experiment separately, use the item numbers listed at the bottom of this description to search and add to your cart. Description The torsion pendulum after Pohl can be used to investigate free or forced harmonic rotational oscillations. An electromagnetic eddy current brake damps these oscillations to a greater or lesser extent, depending on the set current. The torsion pendulum is excited to forced oscillations by means of a motor-driven eccentric rod. The aim of the first experiment is to investigate free harmonic rotational oscillations of the type f(t) = f0 · cosvt · e–d · t where v = öv2 0 – d2 v0: characteristic frequency of torsion pendulum To distinguish between oscillation and creepage, the damping constant F is varied to find the current I0 which corresponds to the aperiodic limiting case. In the oscillation case, the angular frequency v is determined for various damping levels from the oscillation period T and the damping constant d by means of the ratio fn +1 = e– d · T fn 2 of two sequential oscillation amplitudes. Using the relationship v2 = v20 – d2 we can determine the characteristic frequency v0. In the next experiment (P1.5.3.3), the torsion pendulum is excited to oscillations with the frequency v by means of a harmonically variable angular momentum. To illustrate the resonance behavior, the oscillation amplitudes determined for various damping levels are plotted as a function of v2 and compared with the theoretical curve f0 =M0 ·1I ö(v2 – v20)2 + d2 · v2 I: moment of inertia of torsion pendulum