【2017年整理】电场强度与电势梯度.ppt

空间电势相等的点连接起来所形成的面称为等势面. 为了描述空间电势的分布，规定任意两相邻等势面间的电势差相等. 一 等势面（电势图示法） 在静电场中，电荷沿等势面移动时，电场力做功 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 　规定：电场中任意两相邻等势面之间的电势差相等，即等势面的疏密程度同样可以表示场强的大小． Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 电场线和等势面的关系 1）电场线与等势面处处正交. （等势面上移动电荷，电场力不做功.） 2）等势面密处电场强度大；等势面疏处电场强度小. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 二 电场强度与电势梯度 电场中某一点的电场强度沿某一方向的分量，等于这一点的电势沿该方向单位长度上电势变化率的负值. 等势面法线方向指向电势增加的方向 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 任一点场强为该点电势沿等势面法线方向单位长度的变化率的负值 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 直角坐标系中 利用电场强度叠加原理 利用高斯定理 利用电势与电场强度的关系 物理意义 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 思考：在某电场区域内的电场线（实线）和等势线（虚线）如图所示，已知a、b两点的电势分别为-50V、-20V，则a、b连线的中点c的电势应该是 （A）等于-35V （B）大于-35V （C）小于-35V （D）无法确定 （B） Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例1 求一均匀带电细圆环轴线上任一点的电场强度. 解 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例2 半径为R的带电细圆环，线密度 =0|cos|，0为常数，为R与y轴的夹角,求圆环轴线上任一点的电场强度与电势. 解 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evalu