13.10 Resonance Graphs

Resonance Graphs

• 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 & Resonance

• 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 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

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Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.