Ever experienced the voice of a highly trained singer break a wine glass? Or when a bridge you are walking on suddenly starts vibrating. These are the effects of a well known process called resonance. Every object vibrates, rather oscillates at a certain natural frequency. Frequency is the number of oscillations a wave creates per unit of time and amplitude is its maximum range, it is a measure of intensity, loudness or power of a wave such as sound wave.
Resonance occurs when amplitude of an object’s oscillations is increased by the matching vibrations of another object. This happens when the natural frequency of a vibrating object matches with the frequency of vibrating forces around it. The effect is that it vibrates at a higher amplitude than as it does normally. When a tuning fork is placed near a vibrating string, its edges start vibrating due to resonance. This helps in tuning the strings of musical instruments.
Resonance was derived from a Latin word ‘resonare’ which means resound, particularly observed in musical instruments, e.g. when strings of an instrument vibrate and produce sound without being forced to by the player. The frequencies of an object at which the response amplitude is maximum are known as system’s resonant frequencies. At resonant frequencies, small periodic forces around the object have the ability to produce large oscillations in the object, due to storage of vibrational energy. Some of the many forms of resonance are described below.
This refers to resonance of a civil structure in response to surrounding environment vibrations. When designing such structures or mechanical machine engines, the engineers ensure that the resonant frequencies of components are different from that of other oscillating components and are least common. This is to avoid the excessive vibrations which can cause resonant disasters, wherein buildings and bridges collapse due to the violent swaying motions. This resonance maybe stimulated by the vibrations of vehicles on road, or footfall, etc.
This is the same as mechanical resonance, but within the frequency range of human hearing. The sound created in a trumpet in response to vibrations of sound of the player, strings of musical instruments in response to vibration of its body, etc. This too can cause catastrophic failure, like the wine glass case mentioned aforesaid.
This occurs in an electric circuit at a particular resonant frequency, when the current flow rate across the circuit is maximum and resistance is minimum.