Discrete Charges
If the charge in a region consists of N discrete point-like charge carriers like electrons the charge density can be expressed via the Dirac delta function, for example, the volume charge density is:
- ;
where r is the position to calculate the charge, qi is the charge of the charge carriers, labelled conveniently by number using the index i, whose position is ri.
If all charge carriers have the same charge q (for electrons q = −e, the electron charge) the charge density can be expressed through the charge carrier density n(r) by
Again, the equivalent equations for the linear and surface charge densities follow directly from the above relations.
Read more about this topic: Charge Density
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