Characteristics 3 c)4 Sope-÷ c(t)-1-evr)a c0)=a1-e) a 0.632a A 茶 862.16 866.66 T 2T 3T 4T 5T7 >be used to judge whether a first-order system >be used to estimate the time constant1 ( ) (1 ) t T ct a e    (t0) Characteristics 3  be used to judge whether a first-order system  be used to estimate the time constant