To @D01767@, the potential difference divided by the current when there is no @E01974@ in the conductor.
To @A00252@, the real part of @I02988@.
Sources: Green Book, 2nd ed., p. 15 [Terms] [Book] PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 971 [Terms] [Paper]