, cell or some other
source of electrical power) the positive and negative electrodes are labelled,
as well as, a directed arrow with a symbol for the current flowing through
the cell This will tell us the potential difference, V = V (P) – V (N) = e – I r
[Eq (3 38) between the positive terminal P and the negative terminal N; I
here is the current flowing from N to P through the cell]