Example 3 E R Step Response i(t) [1-e ] 09 R 08 0.7 0.632E/R L 06 t= 0.5 R 0.4 03 02 E 0.1 i(t)=0.632 UR 0 R 0 2 3 4 5 6 Time(sec)( ) [1 ] t L R e R E i t    R L t  R E i(t)  0.632 Example 3