The general practice was to put a coulometer (a standard electrolytic
cell) for determining the quantity of electricity  passed from the amount
of metal (generally silver or copper) deposited or consumed However,
coulometers are now obsolete and we now have constant current (I)
sources available and the quantity of electricity Q, passed is given by
Q = It
Q is in coloumbs when I is in ampere and t is in second The amount of electricity (or charge) required for oxidation or
reduction depends on the stoichiometry of the electrode reaction For
example, in the reaction:
Ag +(aq) + e– ® Ag(s)
(2