可以，但是这个表达式只在那个点选择两个圆盘之间才成立，不然结果只能用绝对值表示

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Feel free to ask if there is any other confusion.

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Hello, this is a very basic and standard result. You may even find its formula on textbooks.

For instance, here is what I find on the very first entry when I google for “potential of a disk”.

Notice that the red-boxed part is exactly the same result as I give in my answer, except that it is using sigma instead of rho for the charge density, k instead of 1/(4pi epsilon) for the universal Coulomb factor, R for the radius instead of b, and finally x instead of z for the argument.

ans