“等值代换法”是根据两个量之间具有的数值上的相等关系,通过计算一个量的数值从而间接求出另一个量的一种解题方法。 “等值代换法”是解答物理习题的重要方法之一。兹举例如下: 例1 长为L的导体棒原来不带电,现将一带电量为q的点电荷放在棒左端R处,如图1所示。当达到静电平衡后,棒上感应电荷在棒内中点处产生的场强的 The “equal substitution method” is a problem solving method that indirectly finds another quantity by calculating the value of one quantity based on the numerically equal relationship between the two quantities. The “equal substitution method” is one of the important methods for solving physical problems. Here is an example: Example 1 The conductor bar of length L is originally uncharged. Now a point charge of charge q is placed at the left end of the rod, as shown in Figure 1. When the electrostatic equilibrium is reached, the field induced by the charge induced on the rod at the midpoint of the rod