3.RLC串联电路 用相量法分析R、L、C串联电路的阻抗 R r jOL ++L P+ u L + UR t Ul C== lC U JOC TUC 由KVL:l=llg+u+lc 其相量关系也成立U=Uk+U+UC=RI+joLI-jI C Z=R+JOL-j =IR+j(0L-—Ⅰ=IR+f(X+XC)r OC OC R+jX (R+jX)I DOWNUP DOWN 3. RLC串联电路 用相量法分析R、L、C串联电路的阻抗。 由KVL： . 1 . . . . . . I C U U U UC R I j L I j R L  = + + = +  − I R j X X I C R j L L C   )] [ ( )] 1 [ ( = + +  = +  − R jX I  = ( + ) u = uR + uL + uC 其相量关系也成立 R jX C Z R j L j = +  = +  − 1 L C R u uL uC i + - + - + - + uR - . I R j L + - + - + - . U U L . U C . jωC 1 - + U R