3、求R。,用外加激励法求的电路如图(c)所示,有: 9i+4i=uB=-=52 6 z=R0C=5×0.02=0.l 41 u 图7.1-5(c) l1(t)=1.8eVt≥0−9i + 4i = u 0 = − = 5 i u R R c 5 0.02 0.1s  = 0 =  = ( ) 1.8 V 0 10 1 =  − u t e t t ∴ 图7.1—5 3、求 R0 ，用外加激励法求的电路如图(c)所示，有：