Damping reduces the maximum amplitude of a resonating system and generally lowers its resonant frequency slightly. Greater damping also makes the resonance peak broader and less distinct.
This is part of IB Physics C.4, Standing waves and resonance, and is studied by both SL and HL students.
A driven oscillator receives energy from an external periodic force. Resonance occurs when the driving frequency is close to the system's natural frequency, producing efficient energy transfer and a large steady-state amplitude.
Damping removes mechanical energy from the system, usually through friction or drag. At steady state, the energy supplied by the driving force equals the energy dissipated by damping. Increasing the damping means more energy is lost during each cycle, so the system cannot maintain as large an amplitude.
| Degree of damping | Effect on resonance |
|---|---|
| Light damping | High, narrow resonance peak; resonant frequency is close to the natural frequency |
| Greater damping | Lower, broader resonance peak; resonant frequency shifts slightly lower |
| Critical or heavy damping | Oscillations are strongly suppressed; a distinct resonance peak may disappear |
For an ideal undamped system, the resonant angular frequency equals the natural angular frequency, . With damping, the frequency at maximum amplitude becomes slightly less than . For weak damping, this difference is often very small.
