What is meant by the term 'natural frequency'?

The frequency at which a system oscillates when not driven.

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What happens when the driving frequency is equal to the natural frequency of an oscillating system?

Resonance occurs. 


During resonance the amplitude of oscillations increases significantly.

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What are 'free vibrations'?

Oscillations at the natural frequency when no driving force is applied.

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What happens to the amplitude in free oscillations?

Amplitude is constant as no energy is lost in free oscillations.

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What is meant by the 'driving frequency'?

The frequency of the external periodic force.

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When does resonance occur?

When the driving frequency equals the natural frequency of the oscillating system.

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List some examples of resonance. 

  1. Organ pipe - column of air inside the organ pipes resonates.
  2. Child's swing- a swing being pushed at its natural frequency will resonate.
  3. Radio - a radio is tuned so that the electric circuit resonates at the frequency selected.
  4. Smashing glass - a glass can be smashed when driven by a sound wave at the right frequency.

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