Principle
If an oscillating system is allowed to swing freely it is
observed that the decrease of successive maximum amplitudes is
highly dependent on the damping. If the oscillating system is
stimulated to swing by an external periodic torque, we observe that
in the steady state the amplitude is a function of the frequency
and the amplitude of the external periodic torque and of the
damping. The characteristic frequencies of the free oscillation as
well as the resonance curves of the forced oscillation for
different damping values are to be determined
Benefits
- Long-lasting oscillation due to ball bearings
- Damping via abrasion-resistant eddy current brake
- Simple illustration of the elementary principle of forced oscillations
- Suitable for demonstration and student experiments as well
- Designed for large and clear shadow projection while experimenting
Tasks
- To determine the oscillating period and the characteristic
frequency of the undamped case.
- To determine the oscillating periods and the corresponding
characteristic frequencies for different damping values.
Successive, unidirectional maximum amplitudes are to be plotted as
a function of time. The corresponding ratios of attenuation, the
damping constants and the logarithmic decrements are to be
calculated.
- To realise the aperiodic case and the creeping.
- The resonance curves are to be determined and to be represented
graphically using the damping values of A.
- The resonance frequencies are to be determined and are to be
compared with the resonance frequency values found before
hand.
- The phase shifting between the torsion pendulum and the
stimulating external torque is to be observed for a small damping
value assuming that in one case the stimulating frequency is far
below the resonance frequency and in the other case it is far above
it.
What you can learn about
- Angular frequency
- Characteristic frequency
- Resonance frequency
- Torsion pendulum
- Torsional vibration
- Torque and restoring torque
- Damped/ undamped free oscillation
- Forced oscillation
- Ratio of attenuation/ decrement
- Damping constant
- Logarithmic decrement
- Aperiodic case
- Creeping