For zeroth order system the output will match the input at every instant of time except for a scale factor that is predetermined. There is no attenuation or phase lag for any value of and . Hence it represents an ideal probe or an instrument.
The response of a first order system is:
(Figure 2.20)
(Figure 2.21)
Figure 2.20: Step Response of a First Order System.
that is predetermined. There is no attenuation or phase lag for any value of 
and 
. Hence it represents an ideal probe or an instrument. 
