如图14.20所示，一半径为r2电荷线密度为λ的均匀带电圆环，里边有一半径为r1总电阻为R的导体环，两环共面同心(r2≥r1)，当大环以变角速度w=w(t)绕垂直于环面的中心轴旋转时，求小环中的感应电流，其方向如何？

A .https://assets.asklib.com/psource/2015110114055459111.jpg B .https://assets.asklib.com/psource/2015110114060858725.jpg C .https://assets.asklib.com/psource/2015110114062064666.jpg D .https://assets.asklib.com/psource/2015110114063237571.jpg

A . （λ／4πε）ln2 B . （λ／2πε）ln3 C . （λ／4πε）ln（1／2） D . （λ／2πε）ln2

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' />

(1)P点处的场强; (2)导体表面靠近P点处的电荷元σ₂ΔS所受的电场力 <img src='https://img2.soutiyun.com/ask/2020-11-11/973933401316377.png' />

<img src='https://img2.soutiyun.com/ask/2021-02-14/982167363192026.png' />

一均匀带电球体，半径为R，体电荷密度为ρ，今在球内挖去一半径为r(r＜R)的球体，求证由此形成的空腔内的电场是均匀的，并求其值。

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，电荷线密度为<img src='https://img2.soutiyun.com/shangxueba/ask/65109001-65112000/65111975/957108555344651.png' />,长度为I,细线左端离球心距离为a.设球和线上的电荷分布不受相互作用影响,试求细线所受球面电荷的电场力和细线在该电场中的电势能(设无穷远处的电势为零)。 <img src='https://img2.soutiyun.com/ask/2020-04-30/95710856405086.png' />

如图5-30所示,AB为一根长为2L的带电细棒,左半部均匀带有负电荷一q,右半部均匀带有正电荷q. O点在棒的延长线上,距A端的距离为L;P点在棒的垂直平分线上,到棒的垂直距离为L.以棒的中点C为电势的零点。求O点电势和P点电势。 <img src='https://img2.soutiyun.com/ask/2020-04-30/957108186820535.png' />

一半径为R的帮有一缺口的细圆环,缺口长度为d(d<<r),环上均匀带有正电,电荷为q,如图5-55所示。则圆心o处的场强大小e=_____________，场强方向为_____________。 <img src='https://img2.soutiyun.com/ask/2020-04-30/957114497579253.png' />

如图8.12(a)所示，厚度为b的“无限大”均匀带电平板，其电荷体密度为ρ，求板内外任一点的电场强度。 <img src='https://img2.soutiyun.com/ask/2020-04-21/956329224429095.png' />

<img src='https://img2.soutiyun.com/ask/2020-07-01/962450545452428.png' />

<img src='https://img2.soutiyun.com/ask/2020-09-30/970334285383906.jpg' />

<img src='https://img2.soutiyun.com/ask/2020-05-29/959616701022353.png' /> (1)电介质中的电场强度E、电位移D和极化强度P; (2)电介质表面的极化电荷面密度σ'。

<img src='https://img2.soutiyun.com/ask/2021-02-08/981645647462273.png' />

设有半径为r的半圆形导线,均匀带电,电荷密度为<img src='https://img2.soutiyun.com/ask/2020-11-30/975597671708271.png' />,在圆心处有一单位正电荷,试求它们之间作用力的大小.

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5-38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/2020-11-09/973806805768531.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' />