电路试题库题解(1) 下载本文

f(t)?L?1[F(s)]?L?1[

3(s)4(2)?]22s?4s?4 ?3cos2t?4sin2t?5cos(2t?53.13?)2、图4.2所示电路在零初始条件下is(t)?e?3t?(t)A,C?1F,L?1H,R?0.5?,试求电阻两端电压。

解:画出运算电路如图示。

对电路用弥尔曼定理求解

iS(t) C +

L R u(t) -

图4.2电路图

111s?3? U(s)?s?3?2s?3 1(s?1)(s?1)s?2s?1s??2s令F2(s)=0,可得p1=-1为二重根,所以

k11?(s?1)2F(s) k12?s??1?1?0.5s?3s??1??0.25 s??1+

2/s 1/s s 0.5Ω u(t) -

习题4.2运算电路图

d?1[(s?1)2F(s)]?s??1ds(s?3)2所以 u(t)?0.5e?t?0.25e?tV

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