均匀分布，由此能较简便地得出电容的近似值，然后用Ansoft 软件作有限元仿真，得出更精确的数值.通过对比发现，用均匀带

电近似得出的结果能够正确地反映电容随其尺寸变化的趋势，优于教科书中的平行板电容器公式; 但其数值偏小，原因在于

电荷在极板上并非严格地均匀分布，而是中间少、边缘多.

capacitors varies with the size，respectively. For each kind of capacitor，first it is assumed that charge is distributed

uniformly on the plate，then approximate values of capacitance can be obtained conveniently，afterwards more accurate

values are obtained via finite element simulation using Ansoft. By comparison，it is discovered that results obtained

using the approximation of uniform charge distribution can reflect correctly the tendancy how the capacitance

varies with the size，which is better than the capacitance formula of parallel-plate capacitor in textbooks; however，

those values are smaller，since charge is not strictly distributed uniformly on the plate，but less in the middle and

more on the edge.