What we need to do is get rid of the Coulomb tag that we have - that's how we measure our electron charges - charge, and so we use this epsilon nought quite often, this permativity constant of a vacuum to make that conversion.

怎么量度电子电荷,所以我们会经常用到,这个epsilon，nought记号,这是真空中的介电常数,我们还要指出,这个介电常数。

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