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第三讲 电流与电路 PowerPoint PPT Presentation


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第三讲 电流与电路. 一、电流强度与电流密度. 电荷的定向运动形成电流,电流强度即单位时间内通过导体任一根截面的电量。设在时间间隔 D t 通过某一根截面的电量为 D Q , 则电流强度为. 1.电流强度. I.  S 0. n 0. 2.电流密度. 为给出电流密度的定义,考虑导体中某一给定点 P, 在该点沿电流方向作一单位矢量 n 0 , 并取一面元 D S 0 与 n 0 垂直,设通过 D S 0 的电流强度为 D I, 则定义 P 点处电流密度的大小为. 电流密度的单位为安培/米 2 ( A·m - 2 ) 。. 电流强度与电流密度之间的关系为:.

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第三讲 电流与电路

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