C R lkQ UR 10mA u R u R t=0_|5mA10V010mA010V0 t=0+5mA10V-10mA015mA0-10△例 则 t = 0+时刻  0  t 10mA iS iR iC iL uR uC uL 2k 1k 2k C L u 0V , R  u L  10 V i 15mA , S  i 10 mA , C   i L  5mA u 10V , C  i 0 , R  10V   t 0 10mA L i 10V R i   t 0 5mA 5mA uC 10V C i 0 S i 0 15mA 10mA 0 R u 10V 0 L u 0 S