The last two relationships indicate the amplitude ratio and phase lag for the ultimate response of the first order process. Hence the observations in the last subsection can also be stated in the light of the above results as follows:

•  Sinusoidal output wave has the same frequency as that of input sinusoid

•  Amplitude Ratio between the output wave and input wave is

•  Output wave lags behind the input wave with a phase difference of

III.5.3 Example of frequency response of a second order system

The process is

(III.131)

Put and calculate

(III.132)

Then,

(III.133)

and,

(III.134)