Let us now consider the C-R charging circuit in more detail. Such a circuit is shown in Fig. 8.1 . Let us assume that the capacitor is initially fully discharged, i.e. the p.d. between its plates ( vC ) is zero, as will be the charge, q. Note that the lowercase letters v and q are used because, during the charging sequence, they will have continuously changing values, as will the p.d. across the resistor ( vR ) and the charging current, i. Thus these quantities are said to have transient values.