Natural frequency is the frequency at which a system tends to oscillate in the absence of any driving or damping force.[1]
Free vibrations of any elastic body are called natural vibrations and occur at a frequency called the natural frequency. Natural vibrations are different from forced vibration which happen at frequency of applied force (forced frequency). If forced frequency is equal to the natural frequency, the amplitude of vibration increases manyfold. This phenomenon is known as resonance.[2]
In electrical circuits, s1 is a natural