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What is resonance of a system ? or when a system is called in resonance ?
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asked Nov 23, 2015 | 51 views

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Resonance is a condition of maximum amplitude of a system due to the frequency of external excitation being equal to the natural frequency of the system.

At resonance, a system is able to store and easily transfer energy between two or more different storage modes ( example : Potential to Kinetic and vice versa)

A simple way to understand this is to imagine a child on a swing. At first we give one push the child on the swing ( from now on, swing = child on swing ). We see that the swing begins to oscillate at some frequency. It always reaches its peak point after a fixed interval of time. Therefore we can understand that the time taken for the swing to comeback to it's highest position is its time period (T) (frequency=1/T) This can be said to be the swings natural frequency.. If we apply a force, every time the swing reaches it's maximum height (i.e at fixeed time intervals, at the natural frequency of the swing), we will see that the height of the oscillation of spring increases by a good amount. This is a very simple example of resonance.

Resonance can occur with any kind of frequency or waves. there is mechanical resonance, acoustic resonance, electromagnetic resonant, etc. Resonant systems can be used to generate vibrations of a specific frequency (e.g. musical instruments), or pick out specific frequencies from a complex vibration containing many frequencies

resonance is a frequency level of any rotating body or oscillating body, if normal frequency of  any rotating body approaches towards the natural frequency of it's own  it  leads to rising of resonance . At this level maximum vibration occure in body(i.e. shaft) which leads to bending , twisting  and damaging of body.

let wis any normal frequency of any rotating body(i.e Shaft) and Wn be its natural frequency.

then , for satisfying resonance condition ,

wi=Wn      (Resonance)

• where Wn=(k/m)0.5
• w= rotating frequency       (from X= xsinwt)