如习题4.6图所示的无限网格电路,全部电阻的阻值相同,设为r,求A和B之间的等效电阻R_AB.

电路如习题4-5图所示，其中R=2Ω，L=1H，C=0.01F，u_C=0，若电路的输入电流为 <img src='https://img2.soutiyun.com/ask/uploadfile/5361001-5364000/1dc19a2e7111fdeba57ad82a24868489.png' />

A．M变亮，N亮度不变 B．M变暗，N亮度不变 C．M变亮，N变暗 D．M亮度不变，N变暗

<img src='https://img2.soutiyun.com/ask/2020-08-31/967720818304797.png' />

练习题4-12图所示电路;(1)试求单口网络N₂的等效电阻;(2)求出当N₂与N₁相连时的端口电压u₂;(3)试用置换定理求电压u_o。 <img src='https://img2.soutiyun.com/ask/2020-08-24/967136830775237.png' />

<img src='https://img2.soutiyun.com/ask/2020-08-24/967132990075562.png' />

<img src='https://img2.soutiyun.com/ask/2020-09-01/967832598578661.png' />

<img src='https://img2.soutiyun.com/ask/2020-08-24/967136357397162.png' /><img src='https://img2.soutiyun.com/ask/2020-08-24/967136393334217.png' /><img src='https://img2.soutiyun.com/ask/2020-08-24/96713640161069.png' /> <img src='https://img2.soutiyun.com/ask/2020-08-24/96713641297734.png' />

<img src='https://img2.soutiyun.com/ask/2020-08-24/967130110990887.png' />

求图所示的含受控源电路中，R_L两端的电压U。 <img src='https://img2.soutiyun.com/ask/2020-03-09/952634038812525.jpg' />

<img src='https://img2.soutiyun.com/ask/2020-09-01/967818721851958.png' />

电路如练习题8-12图所示，已知u_s=100cos(20t)V。 (1)计算<img src='https://img2.soutiyun.com/ask/2020-08-28/967470801948578.png' /> (2)绘相量图表面(1)中各相量; (3)求<img src='https://img2.soutiyun.com/ask/2020-08-28/967470841053815.png' />的相位关系; (4)写出i、u_ab、u_bc及u_cd。 <img src='https://img2.soutiyun.com/ask/2020-08-28/96747081020605.png' />

三块质量均为m的相同物块叠放在水平面上，如习题2-16图所示。已知各接触面间的摩擦因数均为μ。 <img src='https://img2.soutiyun.com/ask/2020-04-06/955036516628184.png' /> (1)现有一水平力F作用在最底下的物块上，使之从上面两物块下抽出，则F至少为多大？ (2)若水平力F作用在中间的物块上，使它从上、下两物块中抽出，则F至少为多大？

如习题1.12图所示,空间有两个球,球心间距离小于半径之和,因此有一部分重叠(见图).今使一球充满密度为ρ的均匀正电荷,另一球充满密度为-ρ的均匀负电荷,以至于重叠区域无电荷.求这重叠区域内的电场强度E,说明E是匀强电场: <img src='https://img2.soutiyun.com/ask/2020-08-28/967465752450763.png' />

在题5-7-5图所示的电阻电感串联电路中,若电流i(t)=0.8Ssin314t A,试求电压u_R(t)、u_L(t)和u(t),并绘出波形图和相量图. <img src='https://img2.soutiyun.com/ask/2020-10-10/971171923335419.png' />

<img src='https://img2.soutiyun.com/ask/2020-08-25/967204245200412.png' />

A．各相电灯中电流均为零 B．各相电灯中电流不变 C．各相电灯上电压不变 D．各相电灯上电压将重新分配，高于或低于额定值，因此有的不能正常发光，有的可能烧坏灯丝

<img src='https://img2.soutiyun.com/ask/2020-08-25/967210781527269.png' /><img src='https://img2.soutiyun.com/ask/2020-08-25/967210789488724.png' /> <img src='https://img2.soutiyun.com/ask/2020-08-25/967210797738196.png' />

<img src='https://img2.soutiyun.com/ask/2020-07-16/963764961197678.png' />

电路如练习题8-13图所示，已知i_s(t)=cos(t+90°)A，试求稳态电压u(t)，并绘相量图。 <img src='https://img2.soutiyun.com/ask/2020-08-28/967470947804921.png' />

<img src='https://img2.soutiyun.com/ask/2020-08-24/967136592941634.png' /><img src='https://img2.soutiyun.com/ask/2020-08-24/967136602053155.png' /><img src='https://img2.soutiyun.com/ask/2020-08-24/967136609348572.png' /><img src='https://img2.soutiyun.com/ask/2020-08-24/967136618306084.png' /> <img src='https://img2.soutiyun.com/ask/2020-08-24/967136626942578.png' />