• A graph of driving frequency?f?against amplitude?A?of oscillations is called a?resonance curve. It has the following key features:
  • When?f?<?f0, the amplitude of oscillations increases
  • At the peak where?f?=?f0, the amplitude is at its maximum. This is?resonance
  • When?f?>?f0, the amplitude of oscillations starts to decrease

The maximum amplitude of the oscillations occurs when the driving frequency is equal to the natural frequency of the oscillator

• Damping?reduces?the amplitude of resonance vibrations
• The height and shape of the resonance curve will therefore change slightly depending on the degree of damping
  • Note:?the natural frequency?f0?of the oscillator will remain the same

   

• As the degree of damping is increased, the resonance graph is altered in the following ways:
  • The amplitude of resonance vibrations?decrease, meaning the peak of the curve lowers
  • The resonance peak?broadens
  • The resonance peak moves slightly to the?left?of the natural frequency when heavily damped

   

• Therefore, damping reduced the sharpness of resonance and reduces the amplitude at resonant frequency

As damping is increased, resonance peak lowers, the curve broadens and moves slightly to the left