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(IIIa)
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(IVa)
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(Va)
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§ 20. For some purposes, a different form of some equations is more appropriate.
The first of the three (IV) summarized relations is namely
where, by equation (IIa), we can write for the last three members
which is nothing else than the first component of
Accordingly, we obtain instead of (IVa)
Furthermore, the current can be entirely eliminated. The first of equations (IIIa) becomes, when we consider (4a) and (Ia),
By that it follows, if we define a new vector by means of the equation
thus
If we now introduce the sign for the electric force-action on stationary ions, we obtain the following set of formulas