Resonance

Resonance effect for various input frequencies and damping coefficients

In physics, resonance is the tendency of a system to vibrate with increasing amplitudes at some frequencies of excitation. These are known as the system's resonant frequencies (or resonance frequencies). The resonator may have a fundamental frequency, and any number of harmonics.

An example of useful effect of resonant frequency is a guitar string which makes a characteristic noise when it is touched. The noise depends on how thick or slack the string is.

Another example can be seen in a playground swing. There is one specific rate at which you must push away a person on a swing to cause the swing to go high. This rate is the resonant frequency.

In earthquake engineering, on contrary, any possibility of a resonance is detrimental for the building structure.

The Kirkwood gap and other connections among orbits are caused by orbital resonance.

Resonance Media

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  Pushing a person in a swing is a common example of resonance. The loaded swing, a pendulum, has a natural frequency of oscillation, its resonant frequency, and resists being pushed at a faster or slower rate.

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  Steady-state variation of amplitude with relative frequency \omega/\omega_0 and damping \zeta of a driven simple harmonic oscillator

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  Three identical pendulums of resonance frequency ω0 and damping D=0.05, driven at frequencies ω=2/3ω0, ω=ω0, and ω=4/3ω0. The phase shift is different for each, and the middle, which is driven at the resonance frequency, has the largest swing.

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  Series RLC circuit.

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  A mass on a spring has one natural frequency, as it has a single degree of freedom

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  A standing wave (in black), created when two waves moving from left and right meet and superimpose

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  Standing waves in a string – the fundamental mode and the first 5 harmonics.

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  School resonating mass experiment

Related pages

• Resonator
• Seismic damper
• Vibration control
• Vibration isolation