如图 5－44（a)所示,半径为R的均勾带电球面,带有电荷Q,沿某一半径方向上有一均匀带电细线，电荷

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A . mvhttps://assets.asklib.com/psource/2015102908465835572.jpg ／16B . 3mvhttps://assets.asklib.com/psource/2015102908465835572.jpg ／16C . mvhttps://assets.asklib.com/psource/2015102908465835572.jpg ／4D . 3mvhttps://assets.asklib.com/psource/2015102908465835572.jpg ／4

A . ['0B .https://assets.asklib.com/psource/2015110114080669939.jpg C .https://assets.asklib.com/psource/2015110114081946661.jpg D . ∞

A . （1／2）mv B . （3／2）mv C . （3／4）mv D . （1／4）mv

A . 0 B . C . D . ∞

A .https://assets.asklib.com/psource/2015103015011715312.jpg B .https://assets.asklib.com/psource/2015103015012810244.jpg C .https://assets.asklib.com/psource/2015103015014041530.jpg D .https://assets.asklib.com/psource/2015103015015453297.jpg

A .https://assets.asklib.com/psource/2015103013425061427.jpg B .https://assets.asklib.com/psource/2015103013430314444.jpg C .https://assets.asklib.com/psource/2015103013431765645.jpg D .https://assets.asklib.com/psource/2015103013433392434.jpg

<img src='https://img2.soutiyun.com/ask/uploadfile/6075001-6078000/9ae8096998e91378aab1541edd0baa27.jpg' />

如图7-52所示,两个半径为R的相同的金属环在a 、b两点接触(ab连线为环直径)，并相互垂直故置。电流I沿ab连线方向由a端流入,b端流出,则环中心O点的磁感应强度大小为()。 <img src='https://img2.soutiyun.com/ask/2020-05-09/95788388343784.png' /> A.0 <img src='https://img2.soutiyun.com/ask/2020-05-09/957883663105296.png' />

如图所示,半径为R,电荷线密度为λ(λ>0)的均匀带电圆环,绕圆心且与圆平面垂直的轴以角速度ω转动,求: (1) 圆心O处的磁感应强度B0; (2)轴线上距圆心为a处的一点的磁感应强度B的大小和方向。 <img src='https://img2.soutiyun.com/ask/2020-05-26/95935280876753.png' />

<img src='https://img2.soutiyun.com/ask/2020-10-15/971629097717634.png' /> (1)判别腔的稳定性; (2)求输出端光斑大小; (3)若输出端刚好位于焦距F=0.1m的薄透镜焦平面上，求经透镜聚焦后的光腰大小和位置。

<img src='http://img.shangxueba.cn/files/2016070801/2012q1/ct_xk07031004j_resolve_0044(1201)1.jpg' />

<img src='https://img2.soutiyun.com/ask/uploadfile/9099001-9102000/830665b5f5fe256d269e94008c800e50.jpg' />(1)判别腔的稳定性； (2)求输出端光斑大小； (3)若输出端刚好位于焦距F=0．1m的薄透镜焦平面上，求经透镜聚焦后的光腰大小和位置。

<img src='https://img2.soutiyun.com/ask/uploadfile/9033001-9036000/114604602d9742555e5da37ad2297ec7.jpg' /> 若采用能耗制动停车，电枢应串入多大的电阻？

A、小球带正电 B、P点的电势为 C、电场的电场强度大小为 D、O、C两点间的距离为

<img src='https://img2.soutiyun.com/ask/2021-01-21/980073358567216.jpg' />

一无限长圆柱面,其电荷面密度为<img src='https://img2.soutiyun.com/ask/2020-04-30/957107726124018.png' />.式中<img src='https://img2.soutiyun.com/ask/2020-04-30/957107739133835.png' />为半径R与x轴所夹的角，如图5-21所示。试求圆柱轴线上一点的场强。 <img src='https://img2.soutiyun.com/ask/2020-04-30/957107750785014.png' />

如图5-42所示,在点电荷+Q产生的电场中,将试验电荷q沿半径为R的3/4圆弧轨道由A点移到B点的过程中电场力做功为多少？从B点移到无穷远处的过程中,电场力做功为多少？ <img src='https://img2.soutiyun.com/ask/2020-04-30/957108517163787.png' />

如图5-38所示，一锥顶角为<img src='https://img2.soutiyun.com/ask/2020-04-30/957108379267003.png' />的圆台,上下底面半径分别为r和R ,在它的侧面上均匀带电，电荷面密度为σ,求顶点O的电势。(以无穷远处为电势零点) <img src='https://img2.soutiyun.com/ask/2020-04-30/95710839144979.png' />

<img src='https://img2.soutiyun.com/ask/2020-07-22/964281249714169.png' /> A、<img src='https://img2.soutiyun.com/ask/2020-07-22/96428126108882.png' /> B、<img src='https://img2.soutiyun.com/ask/2020-07-22/96428127157442.png' /> C、<img src='https://img2.soutiyun.com/ask/2020-07-22/964281285841236.png' /> D、<img src='https://img2.soutiyun.com/ask/2020-07-22/964281300748088.png' />